Activities-specific Balance Confidence Scale (ABC Scale)

Purpose

The Activities-specific Balance Confidence Scale (ABC Scale) is a structured questionnaire that measures an individual’s confidence in performing activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
without losing balance.

In-Depth Review

Purpose of the measure

The Activities-specific Balance Confidence Scale (ABC Scale) is a structured questionnaire that measures an individual’s confidence in performing activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
without losing balance.

Available versions

The ABC Scale was developed in 1995 using a convenience sample of 15 clinicians (physical and occupational therapists) and 12 physical therapy patients aged over 65 years. Clinicians were asked to ‘name the 10 most important activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
essential to independent living, that while requiring some position change or walking, would be safe and nonhazardous to most elderly persons’. Seniors were asked the same question, in addition to the question: ‘Are you afraid of falling during any normal daily activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
, and if so, which ones?’ (Powell & Myers, 1995). Items were chosen to include a number of difficult activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
that potentially posed some hazard. A 0-100% response continuum was chosen to assess self-efficacy.

A modified version of the ABC Scale (ABC-Simplified [ABC-S]) was developed to (a) improve user friendliness by simplifying the cue question and response format; and (b) improve the scale’s congruence with public health falls prevention strategies by removing the final question regarding walking in icy conditions (Filiatrault et al., 2007). The psychometric properties of the ABC-S Scale were tested among a sample of 197 community-dwelling seniors. The ABC-S Scale has demonstrated high internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. (reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of "true" variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to "noise" in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
index 0.86) and good convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
(statistically significant associations with perceived balance; performances on the one-leg stance, tandem stance, tandem walking, functional reach, and lateral reach [on the right side] tests; fear of falling; and occurrence of falls in the previous 12 months). Analyses also showed differing degrees of difficulty across items, allowing for a determination of the scale’s item hierarchy. However, no testing of the ABC-S Scale has been conducted with a strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. population.

A 6-item version of the ABC Scale (ABC-6) was also developed for clinical and research use. It includes 6 activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
from the original ABC Scale on which participants demonstrated least confidence (Peretz et al., 2006). In a study conducted among a sample of 35 community-dwelling seniors, it has been shown to be a valid and reliable measure of balance confidence among community-dwelling adults. The scale could also differentiate confidence levels between fallers and non-fallers (Schepens et al., Goldberg, & Wallace, 2010). To date, no psychometric testing of the 6-item version of the ABC Scale has been conducted with a strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. population.

Features of the measure

Original items:
The ABC Scale consists of 16 questions that require the patient to rate his/her confidence that he/she will not lose balance or become unsteady while performing the following activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
:

1. Walking around the house
2. Walking up or down stairs
3. Bending over to pick up a slipper from the front of a closet floor
4. Reaching for a small can off a shelf at eye level
5. Standing on tiptoes and reaching for something above his/her head
6. Standing on a chair to reach for something
7. Sweeping the floor
8. Walking outside the house to a car parked in the driveway
9. Getting into or out of a car
10. Walking across a parking lot to the mall
11. Walking up or down a ramp
12. Walking in a crowded mall where people rapidly walk past
13. Being bumped into people as they walk through the mall
14. Stepping on to or off an escalator while holding onto a railing
15. Stepping onto or off an escalator while holding onto parcels (so that they are not able to hold the railing)
16. Walking outside on icy sidewalks

If the patient does not currently perform the activity, he/she is instructed to imagine how confident he/she might be if he/she had to do the activity. If the patient normally uses a mobility aid to do the activity, he/she is instructed to rate his/her confidence level as if he/she was using this aid during the activity.

Scoring:
The patient is asked to rate his/her confidence performing activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
without losing his/her balance or becoming unsteady. The original scale is a 0% to 100% continuous response scale. However, in a more recent publication, Myers (1999), replaced the 0%-to-100% continuous response scale with an 11-point response scale that includes 10% anchor increments (0%, 10%, . . ., 100%).

0%	10%	20%	30%	40%	50%	60%	70%	80%	90%	100%
No confidence										Completely confident

The overall score is calculated by adding the item scores and dividing the total by 16 (i.e. the number of items). This total score ranges from 0% to 100%.

Myers et al. (1998) use the following cut-off scores to define level of functioning among active older adults:

• Lower than 50 %: low level of physical functioning
• 50-80 %: moderate level of physical functioning
• Above 80 %: high level of physical functioning

What to consider before beginning:
The ABC Scale provides a subjective measure of balance confidence. Scores are not based on clinician observation of performance. Clinicians should also consider factors such as self-esteem and insight when using the ABC Scale.

Time:
The original ABC Scale takes approximately 10-20 minutes to administer.

Training requirements:
No training requirements have been specified for the ABC Scale.

Equipment:
The ABC Scale is a structured questionnaire that does not require specific equipment.

Alternative forms of the Activities-specific Balance Confidence Scale

None.

Client suitability

Can be used with:

• Individuals with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. and other neurological conditions (Moore et al., 2014)
• Individuals with vestibular disorders (Jarlsater & Mattsson, 2003)
• Individuals with lower-limb amputation (Miller, Deathe & Speechley, 2003)
• Individuals with Parkinson’s Disease (Franchignoni et al., 2014)
• Community-dwelling seniors (Myers et al., 1996 ; Myers et al., 1998; Filiatrault et al., 2007)

Should not be used with:

• The ABC Scale is not suitable for individuals with limited insight into their balance impairments. It is not recommended for patients who do not have a rehabilitation goal of improving balance confidence (Moore et al., 2018).

In what languages is the measure available?

Canadian French (Salbach et al., 2006; Filiatrault et al., 2007)
Chinese (Hsu & Miller, 2006; Mak et al., 2007)
Dutch (van Heuvelen et al., 2005)
English (Powell & Myers, 2005)
German (Schott, 2008)
Hindi (Moiz et al., 2017)
Korean (Jang et al., 2003)
Portuguese (Marques et al., 2013)
Swedish (Nilsagard & Forsberg, 2012)
Turkish (Karapolat et al., 2010)

Summary

What does the tool measure?	Self-perceived confidence with mobility.
What types of clients can the tool be used for?	The ABC Scale can be used with, but is not limited to, patients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain..
Is this a screeningTesting for disease in people without symptoms. or assessment tool?	ScreeningTesting for disease in people without symptoms. tool.
Time to administer	10-20 minutes.
ICF Domain	Activity
Versions	ABC-CF (Salbach et al., 2006) ABC-Simplified (Filiatrault et al., 2007) ABC-6 (Peretz et al,2006)
Other Languages	French Canadian, Chinese, Dutch, German, Hindi, Korean, Portuguese, Swedish, Turkish.
Measurement Properties
ReliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of “true” variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to “noise” in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .	Internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency.: – Two studies have reported high internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of the ABC Scale in a strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. population (Botner et al, 2005; Salbach et al, 2006). – One study reported high internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of the ABC-CF Scale in a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population (Salbach et al, 2006). – One study reported high internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of a Swedish translation of the ABC Scale in a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population (Nilsagard & Forsberg, 2012). Test-retest: One study examined test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society). of the ABC Scale within a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population and reported excellent test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society). of the overall score and adequate to excellent item level test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society). (Botner et al, 2005). Intra-rater: Intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings. of the ABC Scale has not been examined. Inter-rater: Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept. of the ABC Scale has not been examined.
ValidityThe degree to which an assessment measures what it is supposed to measure.	Content: One study conducted factor analysis of the ABC Scale within a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population and results revealed two factors: perceived low-risk activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function. and perceived high-risk activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function. (Botner et al, 2005). Criterion: Concurrent: Concurrent validityTo validate a new measure, the results of the measure are compared to the results of the gold standard obtained at approximately the same point in time (concurrently), so they both reflect the same construct. This approach is useful in situations when a new or untested tool is potentially more efficient, easier to administer, more practical, or safer than another more established method and is being proposed as an alternative instrument. See also “gold standard.” of the ABC Scale has not been examined within a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population. Predictive: Predictive validityA form of criterion validity that examines a measure’s ability to predict some subsequent event. Example: can the Berg Balance Scale predict falls over the following 6 weeks? The criterion standard in this example would be whether the patient fell over the next 6 weeks. of the ABC Scale has not been examined within a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population. Construct: Convergent/Discriminant: – Three studies (Botner et al., 2005; Salbach et al., 2006; Nilsagard & Forsberg, 2012) have examined convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other. of the ABC Scale within a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population and reported : an adequate correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation. with the Berg Balance Scale (BBS), gaitThe pattern of walking, which is often characterized by elements of progression, efficiency, stability and safety. speed, 6 Minute Walk Test (6MWT), Barthel Index (BI), Functional AmbulationThe ability to walk, with or without the aid of appropriate assistive devices (such as canes or walkers), safely and sufficiently to carry out mobility-related activities of daily living (ADLs). From Perry et al (1995), functional ambulation is referred to as walking in parallell bars for exercise at a speed of about 10/cm per second. Categories (FAC) and modified Rivermead Mobility Index (RMI); and adequate negative correlations with the Timed Up and Go test (TUG) and 10-m timed walk test. Correlations with the Medical Outcomes Study 36-Item Short-Form Health Survey – Physical function subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society). (SF-36 PF) ranged from excellent to poor among studies. – Two studies (Salbach et al., 2006; Nilsagard & Forsberg, 2012) have examined divergent validityThe degree to which an assessment measures what it is supposed to measure. of the ABC Scale within a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population and reported: an adequate correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation. with the EQ-5D visual analog scale (EQ VAS); an adequate negative correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation. with the Geriatric DepressionIllness involving the body, mood, and thoughts, that affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. A depressive disorder is not the same as a passing blue mood or a sign of personal weakness or a condition that can be wished away. People with a depressive disease cannot merely “pull themselves together” and get better. Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people with depression. Scale (GDS); and a low correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation. with the SF-36 Mental component score. – One study (Salbach et al., 2006) examined convergent / divergent validityThe degree to which an assessment measures what it is supposed to measure. of the ABC-CF Scale and reported: an excellent correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation. with the EQ VAS; an excellent negative correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation. with the GDS; adequate correlations with the SF-36 PF, BBS, walking speed, 6MWT and BI; and an adequate negative correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation. with the TUG. Known Groups: Known-group validityThe degree to which an assessment measures what it is supposed to measure. of the ABC Scale has not been examined within a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population.
Floor/Ceiling Effects	One study (Salbach et al., 2006) reported no floor/ceiling effects for the total score of the ABC Scale or the ABC-CF Scale in a sample of patients with subacute/chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain., but noted a floor effectThe floor effect is when data cannot take on a value lower than some particular number. Thus, it represents a subsample for whom clinical decline may not register as a change in score, even if there is worsening of function/behavior etc. because there are no items or scaling within the test that measure decline from the lowest possible score. See also “ceiling effect.” for 3 items and a ceiling effectA ceiling effect occurs when test items aren’t challenging enough for a group of individuals. Thus, the test score will not increase for a subsample of people who may have clinically improved because they have already reached the highest score that can be achieved on that test. In other words, because the test has a limited number of difficult items, the most highly functioning individuals will score at the highest possible score. This becomes a measurement problem when you are trying to identify changes – the person may continue to improve but the test does not capture that improvement. Example: A memory test that assesses how many words a participant can recall has a total of five words that each participant is asked to remember. Because most individuals can remember all five words, this measure has a ceiling effect. See also “floor effect.” for 8 items of both scales.
SensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also “Specificity.” / SpecificitySpecificity refers to the probability that a diagnostic technique will indicate a negative test result when the condition is absent (true negative).	Not reported.
Does the tool detect change in patients?	No studies have reported on the responsivenessThe ability of an instrument to detect clinically important change over time. of the ABC Scale within a strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. population.
Acceptability	The ABC Scale is non-invasive and quick to administer. The items are considered reflective of real-life activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function. .
Feasibility	The ABC Scale is free and is suitable for administration in various settings. The assessment requires minimal specialist equipment or training.
How to obtain the tool?	The print version of the scale may be freely reproduced for student training, research and clinical practices in which therapists and assistants use the scale to assess fewer than 1000 patients per year. Contact primary developer and copyright holder, Dr.Anita Myers at amyers@uwaterloo.ca.

Psychometric Properties

Overview

A literature search was conducted to identify all relevant publications on the psychometric properties of the Activities-specific Balance Confidence (ABC Scale). While numerous studies have been conducted on the use of the ABC Scale with other client populations, this review specifically addresses the psychometric properties of the ABC Scale with individuals with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain.. Three studies were identified (Salbach, Mayo, Hanley, Richards, & Wood-Dauphinee, 2006; Botner, Miller, & Eng, 2005; Nilsagard & Forsberg, 2012). The original paper by Powell & Myers (1995) has also been included below, although please note that this study uses a mixed population of community-dwelling adults and patients receiving physical therapy services; the number of participants who had a strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. was not specified.

Floor/Ceiling Effects

Salbach et al. (2006) examined floor/ceiling effects of the ABC Scale and the ABC-CF Scale in a sample of 86 participants (n=51 and 35, respectively) with subacute/chronic strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. and residual walking deficits. The authors reported a floor effectThe floor effect is when data cannot take on a value lower than some particular number. Thus, it represents a subsample for whom clinical decline may not register as a change in score, even if there is worsening of function/behavior etc. because there are no items or scaling within the test that measure decline from the lowest possible score. See also "ceiling effect."
(whereby more than 20% of participants reported ‘no confidence’ or 0%) for 3 items of both scales; and a ceiling effectA ceiling effect occurs when test items aren't challenging enough for a group of individuals. Thus, the test score will not increase for a subsample of people who may have clinically improved because they have already reached the highest score that can be achieved on that test. In other words, because the test has a limited number of difficult items, the most highly functioning individuals will score at the highest possible score. This becomes a measurement problem when you are trying to identify changes - the person may continue to improve but the test does not capture that improvement. Example: A memory test that assesses how many words a participant can recall has a total of five words that each participant is asked to remember. Because most individuals can remember all five words, this measure has a ceiling effect. See also "floor effect." (whereby more than 20% of participants reported ‘complete confidence’ or 100%) for 8 items of both scales. There were no floor/ceiling effects for the total score of either scale.

Botner et al. (2005) reported that more than 80% of their study sample (n=77 participants with chronic strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain.) scored between 40% and 80%, suggesting minimal floor or ceiling effects in their sample.

Reliability

The ABC Scale was developed using a convenience sample of 15 clinicians (physical and occupational therapists) and 12 physical therapy patients aged over 65 years (Powell & Myers, 1995).

Internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency.:
Powell & Myers (1995) examined internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of the ABC Scale in a sample of 102 community-dwelling adults aged over 65 and a convenience sample of 18 high-mobility and 7 low-mobility physiotherapy outpatients, using Cronbach’s alpha. The authors reported high internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. (a = 0.96). Stepwise deletion of each item did not alter internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency..

Botner et al. (2005) examined internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of the ABC Scale in a sample of 77 participants with chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain., using Cronbach’s alpha. Results revealed high internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. (a=0.94). Stepwise deletion did not alter internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. (a=0.93 – 0.94).

Salbach et al. (2006) examined internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of the ABC Scale and the ABC-CF Scale in a sample of 86 participants (n=51, 35 respectively) with subacute/chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. and residual walking deficit. The authors reported high internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. for both scales (a= 0.94, 0.93 respectively), measured using Cronbach’s alpha. Stepwise deletion of each item did not improve internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of either scale.

Nilsagard & Forsberg (2012) examined internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. of a Swedish translation of the ABC Scale in a sample of 37 patients with acute/subacute strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain., using Cronbach’s alpha. Participants were retested 3 months later (n=31). The authors reported high internal consistencyA method of measuring reliability . Internal consistency reflects the extent to which items of a test measure various aspects of the same characteristic and nothing else. Internal consistency coefficients can take on values from 0 to 1. Higher values represent higher levels of internal consistency. at both time points (a= 0.97, 0.94 respectively).

Absolute reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of "true" variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to "noise" in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
:
Salbach et al. (2006) examined absolute reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of “true” variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to “noise” in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
of the ABC Scale and the ABC-CF Scale in a sample of 86 participants (n=51, 35 respectively) with subacute/chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. and residual walking deficit. Standard error of measurement of the ABC Scale was 5.05, and standard error of measurement of the ABC-CF Scale was 5.13.

Scalability:
Powell & Myers (1995) examined scalability of the ABC Scale in a sample of 102 community-dwelling adults aged over 65 and a convenience sample of 18 high-mobility and 7 low-mobility physiotherapy outpatients. Scalability encompassed (a) absence of idiosyncratic items, (b) ability of items to discriminate between respondents, and (c) presence of a fixed relation between items. Hierarchicality was measured using Mokken’s Stochastic Cumulative Scaling program (MSP), which revealed a strong cumulative scale (H coefficient = 0.59), and excellent reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of “true” variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to “noise” in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
(Rho coefficient = 0.95).

Test-retest:
Powell & Myers (1995) examined 2-week test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
of the ABC Scale with a sample of 21 community-dwelling seniors. Results revealed excellent overall test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
(r=0.92, p<0.001). Correlations between the test-retest scores was not significant for two items (car transfers, r=0.19; walking in the home, r=0.36).

Botner, Miller and Eng (2005) examined 4-week test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
of the ABC Scale with a sample of 24 participants with chronic strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain., using intra-class correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases - for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases - for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
coefficients. Results indicated excellent test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
of the overall score (ICC = 0.85; 95% CI 0.68-0.93), and adequate to excellent item level test-retest reliabilityA way of estimating the reliability of a scale in which individuals are administered the same scale on two different occasions and then the two scores are assessed for consistency. This method of evaluating reliability is appropriate only if the phenomenon that the scale measures is known to be stable over the interval between assessments. If the phenomenon being measured fluctuates substantially over time, then the test-retest paradigm may significantly underestimate reliability. In using test-retest reliability, the investigator needs to take into account the possibility of practice effects, which can artificially inflate the estimate of reliability (National Multiple Sclerosis Society).
(ICC ranged from 0.53 – 0.93).

Intra-rater:
No studies have reported on the intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
of the ABC Scale. Administration of the ABC Scale does not rely on clinician-observation of patient performance.

Inter-rater:
No studies have reported on the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the ABC Scale. Administration of the ABC Scale does not rely on clinician-observation of patient performance.

Validity

Content:
Botner, Miller & Eng (2005) conducted factor analysis of the ABC Scale in a sample of 77 participants with chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain., using principal component analysis with Varimax rotation. Results revealed two components:
Factor 1: perceived low-risk activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
(9 items; 55.7% of the variance); and
Factor 2: perceived high-risk activitiesAs defined by the International Classification of Functioning, Disability and Health, activity is the performance of a task or action by an individual. Activity limitations are difficulties in performance of activities. These are also referred to as function.
(6 items; 12.9% of the variance).
One item (sweeping the floor) loaded almost equally on both components.

Criterion:
Concurrent:
Powell & Myers (1995) examined concurrent validityTo validate a new measure, the results of the measure are compared to the results of the gold standard obtained at approximately the same point in time (concurrently), so they both reflect the same construct. This approach is useful in situations when a new or untested tool is potentially more efficient, easier to administer, more practical, or safer than another more established method and is being proposed as an alternative instrument. See also “gold standard.”
of the ABC Scale by comparison with the Falls Efficacy Scale (FES) in a sample of 102 community-dwelling adults aged over 65 and a convenience sample of 18 high-mobility and 7 low-mobility physiotherapy outpatients. There was an adequate correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
between scales (r=0.84, p<0.001).

Predictive:
No studies have reported on the predictive validityA form of criterion validity that examines a measure’s ability to predict some subsequent event. Example: can the Berg Balance Scale predict falls over the following 6 weeks? The criterion standard in this example would be whether the patient fell over the next 6 weeks.
of the ABC Scale.

Construct:
Convergent/Discriminant:
Powell & Myers (1995) examined convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
in a sample of 102 community-dwelling adults aged over 65 and a convenience sample of 18 high-mobility and 7 low-mobility physiotherapy outpatients. Convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
was measured by comparison with the Physical Self-Efficacy Scale (PSES). There was an adequate correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
(r=0.49, p<0.001) between the ABC Scale and the PSES score, and an excellent correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
between the ABC scale and the PSES physical abilities subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
(r=0.63, p<0.001). There was no significant correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
between the ABC Scale and the PSES general self-presentation subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
(r=0.03).

Powell & Myers (1995) examined discriminant validityMeasures that should not be related are not. Discriminant validity examines the extent to which a measure correlates with measures of attributes that are different from the attribute the measure is intended to assess.
in a sample of 102 community-dwelling adults aged over 65 and a convenience sample of 18 high-mobility and 7 low-mobility physiotherapy outpatients. Discriminant validityMeasures that should not be related are not. Discriminant validity examines the extent to which a measure correlates with measures of attributes that are different from the attribute the measure is intended to assess.
was measured using the Positive and Negative Affectivity Scale (PANAS). Results were non-significant between the ABC Scale and the PANAS overall score, positive affect score and negative affect score.

Botner, Miller and Eng (2005) examined convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the ABC Scale with a sample of 77 participants with chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain., using Spearman’s correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
coefficient. Convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
was measured by comparison with the Berg Balance Scale (BBS) and gaitThe pattern of walking, which is often characterized by elements of progression, efficiency, stability and safety.
speed. Results showed an adequate correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
with both measures (BBS: r=0.36, p<0.001; gaitThe pattern of walking, which is often characterized by elements of progression, efficiency, stability and safety.
speed: r=0.48, p<0.001).

Salbach et al. (2006) examined convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the ABC Scale and the ABC-CF Scale in a sample of 86 participants (n=51, 35 respectively) with subacute/chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. and residual walking deficit, using Spearman correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
coefficients and associated 95% confidence intervals. Convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
was measured by comparison with the BBS, 5-m walking test (comfortable/maximal gaitThe pattern of walking, which is often characterized by elements of progression, efficiency, stability and safety.
speed), Timed Up and Go test (TUG), 6-Minute Walk Test (6MWT), Barthel Index (BI), Medical Outcomes Study 36-Item Short-Form Health Survey – Physical function subscaleMany measurement instruments are multidimensional and are designed to measure more than one construct or more than one domain of a single construct. In such instances subscales can be constructed in which the various items from a scale are grouped into subscales. Although a subscale could consist of a single item, in most cases subscales consist of multiple individual items that have been combined into a composite score (National Multiple Sclerosis Society).
(SF-36 PF), Geriatric DepressionIllness involving the body, mood, and thoughts, that affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. A depressive disorder is not the same as a passing blue mood or a sign of personal weakness or a condition that can be wished away. People with a depressive disease cannot merely “pull themselves together” and get better. Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people with depression.
Scale (GDS), and the EQ-5D visual analog scale (EQ VAS). The ABC Scale showed an excellent correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
with physical function (SF-36 PF: r=0.60), adequate correlations with perceived health status (EQ VAS: r=0.52), balance function (BBS: r=0.42), walking speed (maximum: r=0.43, comfortable: r=0.42), functional walking capacity (6MWT: r=0.40) and functional independence (BI: r=0.37), and adequate negative correlations with functional mobility (TUG: r=-0.34) and depressive symptoms (GDS: r=-0.30). The ABC-CF Scale showed an excellent correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
with perceived health status (EQ VAS: r=0.68), an excellent negative correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
with depressive symptoms (GDS: r=-0.61), adequate correlations with physical function (SF-36 PF: r=0.56), balance function (BBS: r=0.49), walking speed (maximal: r=0.53; comfortable: r=0.48), functional walking capacity (6MWT: r=0.48), functional independence (BI: r=0.45), and an adequate negative correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
with functional mobility (TUG: r=-0.52).

Nilsagard & Forsberg (2012) examined convergent and divergent validityThe degree to which an assessment measures what it is supposed to measure.
of the ABC Scale in a sample of 37 participants with acute/subacute strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain., using Kendall’s coefficient. Participants were retested 3 months later (n=31). Convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
was measured by comparison with the Functional AmbulationThe ability to walk, with or without the aid of appropriate assistive devices (such as canes or walkers), safely and sufficiently to carry out mobility-related activities of daily living (ADLs). From Perry et al (1995), functional ambulation is referred to as walking in parallell bars for exercise at a speed of about 10/cm per second.
Categories (FAC), modified Rivermead Mobility Index (m-RMI), TUG, 10-m timed walk test, SF-36 Physical component (SF-36 PS), and the 12-item walking scale. The ABC Scale showed significant adequate correlations at both time points with the FAC (r=0.40, 0.49) and the modified RMI (r=0.38, 0.46), and an adequate to low correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
with the SF-36 PF (r=-0.33, 0.28). The ABC Scale showed adequate negative correlations at both time points with the TUG (r=-0.46, -0.43), 10-m timed walk test (r=-0.41 at both time points) and 12-item walking scale (r=-0.55, -0.52). Divergent validityThe degree to which an assessment measures what it is supposed to measure.
was measured using the SF-36 Mental component score (SF-36 MF), with which the ABC Scale showed a low correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
at both time points (r=0.22, 0.12).

Known Group:
Powell & Myers (1995) examined known group validityThe degree to which an assessment measures what it is supposed to measure.
in a sample of 102 community-dwelling adults aged over 65 and a convenience sample of 18 high-mobility and 7 low-mobility physiotherapy outpatients. Participants were self-categorized according to the following categories: fallers (57%), injured fallers (38%), fear of falling (57%) and activity avoidance due to fear of falling (30%). There was no significant difference in mean ABC scores between participants who had fallen in the past year and those who had not experienced a fall. There was no significant difference in mean ABC scores between participants who had been injured during a fall and those who had not been injured during a fall. Activity avoidance due to fear of falling was significantly more common in low mobility participants compared to high mobility participants (p<0.001). There was a significant difference (p<0.001) in mean ABC scores between high mobility and low mobility participants (t=9.34, ES=1.5). All ABC Scale items excluding item 4 (reaching at eye level) showed a significant difference between high mobility and low mobility participants, indicating an ability to discriminate between the two groups. Score ranges within high and low mobility groups indicated an adequate range of responses (score range 5% – 84% confidence for low mobility participants, 36% – 95% confidence for high mobility participants).

Responsiveness

Powell & Myers (1995) examined responsivenessThe ability of an instrument to detect clinically important change over time.
of the ABC Scale in a sample of 102 community-dwelling adults aged over 65 and a convenience sample of 18 high-mobility and 7 low-mobility physiotherapy outpatients. Mean scores ranged from 21% confidence (item 16: walking on an icy sidewalk) to 90% (item 4: reaching at eye level).

SensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also “Specificity.”
& SpecificitySpecificity refers to the probability that a diagnostic technique will indicate a negative test result when the condition is absent (true negative).
:
Powell & Myers (1995) examined item specificitySpecificity refers to the probability that a diagnostic technique will indicate a negative test result when the condition is absent (true negative).
of the ABC Scale by comparison with the Falls Efficacy Scale (FES) in a sample of 102 community-dwelling adults aged over 65 and a convenience sample of 18 high-mobility and 7 low-mobility physiotherapy outpatients. ABC Scale items 3-6 correlated significantly with the FES item ‘reach into cabinets or closets’ (r = 0.53-0.67, p<0.001), and ABC Scale items 9-15 correlated with the FES item ‘simple shopping’ (r=0.42-0.75).

References

Activities-specific Balance Confidence Scale. (2013, March 22). Retrieved from URL https://www.sralab.org/rehabilitation-measures/activities-specific-balance-confidence-scale

Botner, E.M., Miller, W.C., & Eng, J. J. (2005). Measurement properties of the Activities-specific Balance Confidence scale among individuals with stroke. Disability and Rehabilitation, 27(4), 156-63.

Filiatrault, J., Gauvin, L., Fournier, M., Parisien, M., Robitaille, Y., Laforest, S., Corriveau, H., & Richard, L. (2007). Evidence of the psychometric qualities of a simplified version of the Activities-specific Balance Confidence scale for community-dwelling seniors. Archives of Physical Medicine and Rehabilitation, 88, 664-72.

Franchignoni, F., Giordano, A., Ronconi, G., Rabini, A., & Ferriero, G. (2014). Rasch validation of the Activities-specific Balance Confidence Scale and its short versions in patients with Parkinson’s Disease. Journal of Rehabilitation Medicine, 46, 532-9.

Hsu, P.C., & Miller, W.C. (2006). Reliability of the Chinese version of the Activities-specific Balance Confidence scale. Disability and Rehabilitation, 28(20), 1287-92.

Jang, S.N., Cho, S.I., Ou, S.W., Lee, E.S., & Baik, H.W. (2003). The validity and reliability of Korean Fall Efficacy Scale (FES) and Activities-specific Balance Confidence scale (ABC). Journal of the Korean Geriatrics Society, 7(4), 255-68.

Jarlsater, S. & Mattsson, E. (2003). Test of reliability of the Dizziness Handicap Inventory and the Activities-specific Balance Confidence scale for use in Sweden. Advances in Physiotherapy, 5, 137-44.

Karapolat, H., Eyigor, S., Kirazli, Y., Celebisoy, N., Bilgen, C., & Kirazli, T. (2010). Reliability, validity, and sensitivity to change of Turkish Activities Specific Balance Confidence Scale in patients with unilateral peripheral vestibular disease. International Journal of Rehabilitation Research, 33, 12-18.

Mak, M.K., Lau, A.L., Law, F.S., Cheung, C.C., & Wong, I.S. (2007). Validation of the Chinese translated Activities-specific Balance Confidence scale. Archives of Physical Medicine and Rehabilitation, 88, 496-503.

Marques, A.P., Mendes, Y.C., Taddei, U., Pereira, C.A.B., & Assumpcao, A. (2013). Brazilian-Portuguese translation and cross cultural adaptation of the activities-specific balance confidence (ABC) scale. Braz J Phys Ther. Mar-Apr; 17(2), 170-178.

Miller, W.C., Deathe, A.B., & Speechley, M. (2003). Psychometric properties of the Activities-specific Balance Confidence scale among individuals with a lower-limb amputation. Archives of Physical Medicine and Rehabilitation, 84, 656-61.

Moiz, J.A., Bansal, V., Noohu, M.M., Gaur, S.N., Hussain, M.E., Anwer, S., & Alghadir, A. (2017). Activities-specific balance confidence scale for predicting future falls in Indian older adults. Clinical Interventions in Aging, 12, 645-651.

Moore, J.L., Potter, K., Blankshain, K., Kaplan, S.L., O’Dwyer, L.C., & Sullivan, J.E. (2018). A core set of outcome measures for adults with neurological conditions undergoing rehabilitation: a clinical practice guideline. Journal of Neurological Physical Therapy, 42, 174-216.

Myers, A.M., Fletcher, P.C., Myers, A.H., & Sherk, W. (1998). Discriminative and evaluative properties of the Activities-specific Balance Confidence (ABC) scale. Journal of Gerontology: Medical Sciences, 53A(4), M287-94.

Myers, A.M., Powell, L.E., Maki, B.E., Holliday, P.J., Brawley, L.R., & Sherk, W. (1996). Psychological indicators of balance confidence: relationship to actual and perceived abilities. Journal of Gerontology: Medical Sciences, 51A(1), M37-43.

Myers, A.M. (1999). Program evaluation for exercise leaders. Waterloo: Human Kinetics.

Nilsagard, Y., & Forsberg, A. (2012). Psychometric properties of the Activities-Specific Balance Confidence Scale in persons 0-14 days and 3 months post stroke. Disability & Rehabilitation, 34(14), 1186-1191.

Peretz, C., Herman, T., Hausdorff, J.M., & Giladi, N. (2006). Assessing fear of falling: can a short version of the Activities-specific Balance Confidence scale be useful? Movement Disorders, 21(2), 2101-5.

Powell, L.E. & Myers, A.M. (1995). The Activities-specific Balance Confidence (ABC) scale. Journal of Gerontology: Medical Sciences, 50A (1), M28-34.

Salbach, N.M., Mayo, N.E., Hanley, J.A., Richards, C.L., & Wood-Dauphinee, S. (2006). Psychometric evaluation of the original and Canadian French version of the Activities-Specific Balance Confidence scale among people with stroke. Archives of Physical Medicine and Rehabilitation, 87, 1597-1604.

Schepens, S., Goldberg, A., & Wallace, M. (2010). The short version of the Activities-specific Balance Confidence (ABC) scale: Its validity, reliability, and relationship to balance impairment and falls in older adults. Archives of Gerontology and Geriatrics, 51, 9-12.

Schott, N. (2008). [German adaptation of the “Activities-Specific Balance Confidence (ABC) scale” for the assessment of falls-related self-efficacy]. Zeitschrift für Gerontologie und Geriatrie, 41, 475-85.

van Heuvelen, M.J., Hochstenbach, J., de Greef, M.H., Brouwer, W.H., Mulder, T., & Scherder, E. (2005). [Is the Activities-specific Balance Confidence Scale suitable for Dutch older persons living in the community?]. Tijdschrift Voor Gerontologie En Geriatrie, 36, 146-54.

See the measure

How to obtain the Activities-specific Balance Confidence Scale

The print version of the scale may be freely reproduced for student training, research and clinical practices in which therapists and assistants use the scale to assess fewer than 1000 patients per year. In all other cases, including: translation into other languages than English, other modifications to the scale itself and/or instructions, use in clinical trials, for commercial or marketing purposes, or in larger scale practices (1,000+ patients per year) and electronic record keeping, permission must be obtained by the researcher or institution. There may be an associated cost.

Dr. Anita Myers is the primary developer and copyright holder of the ABC scale. email: amyers@uwaterloo.ca.