Neurorehabilitation and Neural
Repair
http://nnr.sagepub.com/
Minimal Detectable Change Scores for the Wolf Motor Function Test
Stacy L. Fritz, Sarah Blanton, Gitendra Uswatte, Edward Taub and Steven L. Wolf
Neurorehabil Neural Repair 2009 23: 662 originally published online 4 June 2009
DOI: 10.1177/1545968309335975
The online version of this article can be found at:
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Minimal Detectable Change Scores for
the Wolf Motor Function Test
Neurorehabilitation and
Neural Repair
Volume 23 Number 7
September 2009 662-667
© 2009 The Author(s)
10.1177/1545968309335975
http://nnr.sagepub.com
Stacy L. Fritz, PhD, MSPT, Sarah Blanton, DPT, Gitendra Uswatte, PhD,
Edward Taub, PhD, and Steven L. Wolf, PhD, PT
Background. The Wolf Motor Function Test (WMFT) is an impairment-based test whose psychometrics have been examined by previous
reliability and validity studies. Standards for evaluating whether a given change is meaningful, however, have not yet been addressed.
Objectives. To determine the standard error of measurement (SEM) and minimal detectable change (MDC) for the WMFT. Methods. Data
were collected from 6 university laboratories that participated in the EXCITE national clinical trial and included 96 individuals with
sub-acute stroke (3–9 months). Measurements were made by blinded evaluators who were trained and standardized to administer the
WMFT, which was completed on 2 occasions 2 weeks apart. No intervention was given between testing sessions. Results. The WMFT
Performance Time score has a SEM of 0.2 seconds and a MDC95 of 0.7 seconds. The individual task timed items MDC95 ranged from 1.0
second (turn key in lock) to 3.4 seconds (reach and retrieve) with individual task items demonstrating notablly higher variability than the
average WMFT Performance Time. The average WMFT Functional Ability Scale SEM and MDC95 is 0.1 points. Conclusions. When
assessing the effect of a therapeutic intervention, if an individual experiences an amount of change equal to or greater than the MDC,
then one may be 95% confident that this margin of change is truly larger than measurement error and not a chance result. Thus, the
determination of SEM and MDC in outcome assessments allows researchers and clinicians to distinguish which results are actual differences versus which results are simply changes resulting from error or chance.
Keywords: Reliability; Minimal detectable change; Wolf Motor Function Test; Standard error of measure; Stroke
D
etermining whether therapeutic gains are statistically
significant is important when evaluating results from a
clinical trial; however, the results should also be large enough
to be clinically meaningful. An important first step in establishing standards for meaningful changes is identifying what is
the measurement error on the instruments used to test treatment efficacy. Often times, trials that have a large enough
sample can report significant results, but still have changes on
the outcome measures that are smaller than their measurement
error. Knowing an instrument’s measurement error is also
valuable to clinical practice, because changes after therapy for
individual patients can be compared with the measurement
error to evaluate the meaningfulness of the changes observed
without need for statistical testing.
The Wolf Motor Function Test (WMFT) is one of the most
frequently cited outcome measures used in stroke rehabilitation
studies1–5 and has been used to assess upper-extremity function
in research labs in over 16 countries. This impairment-based
test, developed by Wolf et al6 and later modified by Taub et al,7
quantifies upper extremity movement ability through timed
single or multiple joint motions and functional tasks.
Progressing from proximal to distal joint movement, the test
consists of 15 timed items, 2 strength measures, and a quality
of motor function scale for each of the timed items (6-point
Functional Ability Scale). The WMFT starts with simple
items, such as placing the hand on a table top, and progresses
to more challenging fine motor tasks, such as stacking checkers or picking up a paper clip.
The test was originally devised to assist clinicians in guiding treatment interventions based upon specific joint-related
movement limitations. As evidenced by over 90 citations in
the stroke literature to date, its psychometric properties support the utility of the WMFT in research studies. The reliability and validity of the WMFT have been ascertained in chronic
stroke (Morris et al,8 and Wolf et al,9 respectively) and subacute stroke.10 Used as one of the primary outcome measures
in the EXCITE (Extremity Constraint-Induced Therapy
Evaluation) trial,11 the sensitivity of the instrument was such
that higher functioning participants were differentiated from
lower functioning participants across 6 research sites and
From the Arnold School of Public Health, Department of Exercise Science, Physical Therapy Program, University of South Carolina, Columbia, South
Carolina (SLF); School of Medicine, Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, Georgia (SB);
Departments of Psychology and Physical Therapy, University of Alabama at Birmingham, Birmingham, Alabama (GU); Department of Psychology,
University of Alabama at Birmingham, Birmingham, Alabama (ET); and School of Medicine, Departments of Rehab Medicine, Medicine, and Cell
Biology, Nell Hodgson Woodruff School of Nursing, Health and Elder Care, Emory University, Atlanta VA Rehab R&D Center, Atlanta, Georgia (SLW).
Address correspondence to Stacy Fritz, PhD, MSPT, Department of Exercise Science, Third Floor PHRC, 921 Assembly Street, Columbia SC, 29208.
E-mail: sfritz@mailbox.sc.edu
662
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Fritz et al / Scores for the Wolf Motor Function Test 663 scores were not influenced by hand dominance or affected
side. In healthy individuals without impairments, the WMFT
has been shown to be sensitive to the extent that scores were
significantly different for the dominant versus the nondominant extremities.9 Stability of the WMFT has been supported
by the lack of change in scores from 24 chronic stroke survivors residing in the community tested on 2 occasions separated by approximately 2 weeks.8
While important psychometrics of the WMFT have been
established through previous reliability and validity studies,8–10
further information is needed to fully interpret and apply test
scores. For instance, while reliable, just how far away does an
individual score need to lie from a norm for this difference not
to be considered an error of measurement? How can a
researcher or clinician know if pretherapy to posttherapy
changes on the WMFT exceed the minimal change necessary to
be sure the change observed was not simply due to chance?
Determining the standard error of measurement (SEM) and
minimal detectable change (MDC) of the WMFT can help
clarify the meaning of scores obtained in both research and
clinical settings. The roles of SEM and MDC in test score
interpretation with respect to reliability, measurement error,
and test–retest variation are described below.
Reliability refers to the repeatability of a measurement. If a
test is perfectly error-free then an individual should get the
same score on the test when given on 2 separate occasions12;
this is assuming that the underlying construct being measured
does not change. Thus, reliability indicates the consistency of
a measurement and provides an indication of the amount of
confidence that can be placed in interpretation of results. The
intraclass correlation coefficient (ICC) reflects the degree of
similarity and agreement among measurements and is a ratio
of the between-classes variance to the total variance.12,13 ICCs
permit the comparison of 2 or more repeated measures and
range from 0.0 to 1.0, with higher values indicating a greater
degree of relationship between variables.
The SEM is the standard deviation (SD) of measurement
errors and reflects the extent of expected error in repeated
measurements.12,14 The SEM is expressed in the units of the
measure. Measurement errors are assumed to be normally
distributed; therefore, there is a 95% probability that an individual’s true value would be within 2 SEMs of the original
measurement. Thus, the ICC provides information on the relative reliability of a measure by assessing the degree of association between repeated measurements, and the SEM provides
information on the absolute reliability of a measure by assessing the extent to which a score may vary with repeated measurements on average based on measurement error.12
The SEM reflects the average error in measurement; however, interpreting a change or difference that is larger than the
SEM as a “real” difference or more precisely a difference that
would not be likely by chance is incorrect. For this purpose,
the MDC should be calculated, it reflects the smallest detectable difference that can be considered a “real change,” that
exceeds measurement error by a wide enough margin to not be
considered a chance result. A change in an observed value that
is less than the MDC can be considered similar to an error in
measurement.
The aim of this article is to explore the absolute reliability
of the WMFT as a tool to document upper extremity function
by establishing the SEM and MDC. Specifically, the SEM and
MDC were determined using WMFT data from participants
3 to 9 months after stroke in the EXCITE national clinical trial
who underwent repeated testing separated by a 2-week interval but did not receive Constraint Induced Movement therapy
(CIMT) or any outside intervention during this time.
Methods
Data were gathered by investigators at the 6 EXCITE clinical sites (Emory University, University of Southern California,
University of Alabama at Birmingham, University of Florida,
University of North Carolina-Chapel Hill with Wake Forest
University, and the Ohio State University), all of which had
institutional review board approval. For a full description of
EXCITE trial methodology, see Winstein et al (2003).11
Participants (mean age, 62.3 years; range, 19–90 years) were
assigned to either an immediate or delayed group condition.
The immediate group received 2 weeks of CIMT during this
sub-acute period, while the delayed group received the therapy
1 year later, in the chronic phase of the stroke. The delayed
group’s first and second testing sessions were used in this
analysis, which were separated by approximately 2 weeks. All
participants were required to have the minimal movement
criteria for CIMT, which includes the ability to actively extend
the wrist, thumb, and at least 2 other digits greater than 10
degrees. All EXCITE evaluators were masked to participant
treatment group designation. These study personnel were
trained and standardized to administer the WMFT through a
thorough review of specific instructions and repeated practice.
Evaluator performance was re-examined at yearly intervals
throughout the trial. All components of the test were also standardized, including placement of items, chair, and table.
Statistical Analysis
The total sample for the study was 116 individuals with
sub-acute stroke. Participants who declined to participate (n =
7), withdrew from the study before their second test (n = 12),
or had no score reported for the any tasks on the timed portion
of the WMFT (n = 1) were removed from the data set.
Therefore the final sample size was 96. The normality of average scores for the WMFT (both Performance Timed scores and
Functional Ability Scale scores), were visually verified with
probability plots (P-P) and statistically verified with the
Kolmogorov-Smirnov f test (P > .05). The Functional Ability
Scale test scores met assumptions of normality. Although
functional ability on individual items is rated using an ordinal
scale, the test score is treated as parametric data because the
test score can take on a very large number of values because it
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664 Neurorehabilitation and Neural Repair
is the average of the item scores. The timed portion of the
WMFT, however, required transformation using the natural
log (ln) to meet assumptions of normality so that the intraclass
correlation coefficient (ICC) could be used. The average measures of the ICC were calculated using a 2-way mixed effect
model, with a consistency coefficient.15 The measures for the
ICC were then entered into the following SEM formula:
SD [√(1-ICC)average task scores],
where SD is the standard deviation of the item difference
scores.
For the data that required transformation, the SD of the
transformed item difference score was used. The SD of the
transformed data was used to calculate the SEM so the SD
would be from a normal distribution. The SEM was then transformed back to the original units using the inverse of the natural log. The MDCs were then calculated using the following
formula16–18:
MDC90=1.64*SEM*√2 and the MDC95=1.96*SEM*√2.
where “1.64” in the MDC90 reflects the 90% confidence
interval (CI), the “1.96” in the MDC95 reflects the 95% CI, and
√2 accounts for the additional uncertainty introduced by using
difference scores from measurements obtained at 2 different
time points.19
Calculating the index of reliability for each individual task
item for the Functional Ability Scale score is not appropriate,
as these are scored with ordinal numbers. To calculate the
item-level SEM and MDCs for each timed task, scores of 121
were entered as missing data representing that the participant
was unable to complete or perform the test item. This procedure is both for a practical and theoretical purpose. Practically,
the 121 scores skewed the data and all transformations
attempted did not allow the data to present in a normal distribution. Theoretically, a score of 121 is assigned, not earned;
therefore it does not represent a real score. Thus, all the SEM
and MDCs for the individual timed task items are only applicable to individuals who complete a given task in 120 seconds
or less. Only 16% of the timed items were assigned a score of
121. An additional 5% of the data points, however, could not
be used in calculating the indices of reliability for the individual timed scores because their matched pair was a 121 (eg,
score was < 121 on the first test but equal to 121 on the second). The same procedure used for the average test scores was
then used to calculate the ICC, SEM, MDC90, and MDC95 for
the individual scores, including data transformation. For the
grip strength task (measured in lbs) on the WMFT, scores of
“0” were changed to “0.1” to allow for transformation of data
using SQRT to obtain a normal distribution. The task of weight
to box (in lbs) did not present as a normal distribution with any
attempted transformations, but was still included in the results
and should be interpreted with caution. The averages and standard deviation for the WMFT Performance Timed scores and
Functional Ability Scale scores were calculated. The individual item scores were calculated following exclusion of all the
data with a score of 121. All statistical calculations were completed using SPSS version 16.0.
Results
Sixty men and 36 women participated in this study. Fortythree had right-side hemiparesis, while 53 had left-side hemiparesis; half had dominant-side hemiparesis. The average and item
scores for the individual Performance Time tasks, the strength
tasks, and the Functional Ability Scale scores for the affected
upper-extremity are presented in Table 1. The pretest average
Performance Time score across all items was 28.5 (32.4) seconds and the average posttest score following 2 weeks of no
intervention decreased to 25.8 (30.8) seconds. The average
Functional Ability Scale score improved from a 2.5 (0.7) at
pretest to a 2.6 (0.7).
Results for the relative and absolute reliability indices are
given in Table 2. The Performance Time test score had an ICC
of 0.98 with a MDC95 of 0.7 seconds. The individual task
timed item MDCs ranged from 1.0 seconds (turn key in lock)
to 3.4 seconds (reach and retrieve). The Functional Ability
Scale score ICC was 0.96 with a MDC95 of 0.1 points.
Discussion
This study determined the SEM and MCD values for the
WMFT in a cohort of patients with sub-acute stroke. These
results allow us to determine (a) the range of an individual’s or
group’s true score by using the measured score and SEM and,
(b) by using the MDC, if a patient or group of patients exceeded
the minimal change necessary following therapy, the change
observed is most likely not simply due to error. These data apply
to patients with some residual movement ability 3 to 9 months
after stroke. However, the psychometrics of the WMFT are
similar in chronic and sub-acute patients,10 so this observation
may suggest that these absolute reliability statistics can be
applied to chronic patients also. This hypothesis, however,
should be tested in future research. The interpretation of SEM is
as follows: we are 95% confident the person’s true score was
between [measured score − (2*SEM)] and [measured score +
(2*SEM)]. For example if a participant scored an average of
17.5 seconds on WMFT Performance Time for the more
affected upper extremity, we can be 95% confident that his or
her true score was between 17.5 ± 0.4 seconds, or his true score
was from 17.1 to 17.9 seconds. With such a small SEM and high
ICC, the test score is considered to have excellent reliability.
There is need for caution when using strictly statistical
analysis (ie, P value) as a surrogate for meaningfulness of
change. Mean change scores may demonstrate statistically
significant results, especially when larger samples are used.
For example, although no therapy was received between the
testing sessions in this analysis, there was a significant difference between the first and second testing sessions in WMFT
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Fritz et al / Scores for the Wolf Motor Function Test 665 Table 1 Average and Item Scores for the WMFTa
Item No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Average Time (sec) / Weight (lbs)
Item Description
Pre (SD) Post (SD)
Forearm to table
Forearm to box
Extend elbow
Extend elbow with weight
Hand to table (front)
Hand to box (front)
Weight to box (lbs)
Reach and retrieve
Lift can Lift pencil
Lift paper clip
Stack checkers
Flip cards
Grip strength (lbs)
Turn key in lock
Fold towel
Lift basket
Average score
2.6 (5.0)
5.1 (10.2)
3.3 (9.2)
3.5 (12.1)
1.9 (1.3)
2.4 (4.8)
5.2 (6.0)
1.5 (1.1)
6.3 (7.9)
11.6 (23.2)
10.6 (19.5)
23.8 (23.7)
17.6 (19.2)
9.5 (7.9)
14.7 (19.6)
13.3 (15.9)
9.6 (15.9)
28.5 (32.4)
1.9 (1.7)
3.5 (3.9)
6.0 (17.3)
2.8 (8.9)
1.9 (1.7)
1.7 (1.2)
5.9 (6.5)
1.4 (1.1)
4.7 (4.4)
8.8 (15.5)
7.5 (11.8)
21.2 (22.1)
15.5 (17.3)
10.4 (8.7)
12.4 (16.1)
15.7 (16.4)
10.7 (17.4)
25.8 (30.8)
Average Functional Ability Scale Score
Pre (SD)
Post (SD)
3.0 (0.5)
2.6 (0.8)
2.8 (1.0)
2.8 (0.9)
2.9 (0.6)
2.7 (0.9)
na
2.7 (1.4)
2.4 (0.9)
2.2 (0.9)
2.3 (0.9)
2.0 (0.9)
2.3 (0.8)
na
2.3 (0.9)
2.3 (1.0)
2.2 (1.1)
2.5 (0.7)
3.1(0.6)
2.8(0.8)
3.0(1.0)
2.9(1.0)
3.1(0.6)
3.0(1.0)
3.0(1.3)
2.6(1.0)
2.2(0.9)
2.4(1.0)
2.0(0.9)
2.2(0.8)
2.2(1.0)
2.5(1.0)
2.4(1.0)
2.6(0.7)
Abbreviations: WMFT, Wolf Motor Function Test; SD, standard deviation; na, not applicable.
The average scores for the first testing session (pre) and the second testing session (post) for each item of the WMFT are displayed.
a
Table 2 Reliability Indices for WMFT a
Item No.
Item Description
Average WMFT time score 1
Forearm to table
2
Forearm to box
3*
Extend elbow
4
Extend elbow with weight
5
Hand to table (front)
6
Hand to box (front)
7*
Weight to box (lbs)
8
Reach and retrieve
9
Lift can 10*
Lift pencil
11
Lift paper clip
12
Stack checkers
13
Flip cards
14
Grip strength (lbs)
15
Turn key in lock
16
Fold towel
17
Lift basket
Average WMFT FAS
ICC Point Estimate (95% CI)
SEM 90% MDC
95% MDC
N
0.98(0.96-0.98)
0.80(0.70-0.87)
0.87(0.80-0.92)
0.88(0.82-0.93)
0.81(0.70-0.87)
0.86(0.79-0.91)
0.81(0.70-0.88)
0.94(0.91-0.96)
0.80(0.70-0.86)
0.83(0.73-0.89)
0.78(0.65-0.86)
0.84(0.75-0.90)
0.73(0.53-0.84)
0.91(0.85-0.94)
0.98(0.97-0.99)
0.94(0.90-0.96)
0.91(0.85-0.94)
0.86(0.77-0.92)
0.96(0.94-0.98)
0.2
0.8
0.6
0.6
0.8
0.5
0.7
1.9
1.2
0.7
1.1
0.8
1.1
0.4
0.0
0.4
0.4
0.7
0.1
0.5
1.8
1.4
1.4
2.0
1.3
1.6
4.3
2.8
1.6
2.5
1.8
2.6
1.0
0.1
0.8
1.0
1.7
0.1
0.7
2.1
1.6
1.7
2.4
1.5
1.9
5.2
3.4
2.0
3.0
2.2
3.2
1.2
0.1
1.0
1.2
2.0
0.1
96
92
82
82
86
91
77
96
92
72
71
73
56
73
96
69
69
57
95
Abbreviations: ICC, intraclass correlation coefficient; CI, confidence interval; SEM, standard error of measurement; MDC, minimal detectable change; N, number; WMFT, Wolf Motor Function Test; FAS, Functional Ability Scale.
a
The SEM and MDCs for the average scores were calculated from the average time (seconds) and average Functional Ability Scale (FAS) scores for the more
affected upper extremity. For the individual tasks: (1) all SEM and MDC measurement are in seconds with exception of weight to box and grip strength, which
are in pounds, (2) the individual task SEMs and MDCs apply to only participants who are able to complete the task for the timed tasks, therefore for participants
who are assigned a score of 121, indices are not applicable. For individual items demarcated with an *, the data did not represent a normal distribution following
transformation (P < .01) according to Kolmogorov-Smirnov tests; the indices are still reported because P-P plots are similar to other items.
Performance Time (P = .004, ln transformed, 2-tailed, paired t
test). The importance of statistically significant findings can
be unclear and may simply be due to having a large sample or
substantial similarity in scoring trends across participants (low
standard deviation). The inclusion or development of additional
indices to determine whether data exceed measurement error
(MDC) or whether the results are clinically meaningful (MCID)
can help with interpretation of statistical results. For these data,
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666 Neurorehabilitation and Neural Repair
the average WMFT Performance Time scores exceeded the
MDC95 from the first testing session to the second, with an average change of 2.7 seconds (28.5 to 25.8 seconds; Table 1). This
result would indicate that we can be 95% confident the change
in Performance Time seen in this sample (no intervention) was
not due to measurement error. This “improvement” may be due
to a practice effect, which includes familiarity with the assessment, or to spontaneous recovery. The experimental group,
however, which received CI therapy, had a much larger reduction in Performance Time.20 For this sample, the change in
Functional Ability Scale scores from first to second session was
equal to the MDC95 value.
The absolute reliability is a particularly important statistic for
clinicians because scores from individual patients can be compared with these standards to evaluate whether any changes
observed after therapy are larger than the instrument error, and
hence meaningful. Currently we know the test is highly
reliable,10 but what if a participant scores an average of 17.5
seconds on the first test and 17.0 seconds on the second test?
Can we be confident that this change is an improvement or is the
change simply due to measurement error? The MDC95 score is
0.7 seconds for the average WMFT Performance Time test.
Therefore, to be 95% confident that our participants improved,
their score would have to be less than (17.5 seconds minus 0.7
seconds) or less than 16.8 seconds. If they score less than 16.8
seconds then we are 95% confident that the change is “true” and
not due to measurement error. In addition to the Performance
Time scores, the average Functional Ability Scale scores also
have reliability indices determined. To be 95% confident that
individuals improved on the Functional Ability Scale score, they
must improve their average score by 0.1 points or more.
The results also allow therapists to determine which individual items exceed the minimal detectable change. Due to the
variability in scores and to the assumptions required for parametric statistics, the individual results only apply to participants
who are able to complete a task (scoring less than 121 seconds
on a particular task). While the absolute reliability is established
for the individual task items, the SEM and MDC values for
individual item Performance Time scores were larger (with
wider ICC confidence intervals) than for the aggregate test
score. This discrepancy may be due to changes in patient tone
across particular joints that can affect performance on individual
items, or just the general heterogeneity of upper-extremity
motor deficits after stroke, even among patients whose attributes are defined by the specificity inherent in a clinical study,
like the EXCITE Trial, from whence this participant pool came.
Therefore, using 1 index from WFMT as an assessment presents
decreased reliability. Moreover, validity is not determined at this
time for individual items on the WMFT. Therefore, while absolute reliability is reported for the individual task items, the
authors suggest against using individual item MDCs to evaluate
change, but to use the aggregate test score instead, which does
provide a reliable valid metric.
Several limitations of the current study need to be addressed.
We were unable to distinguish between intrarater/interrater
reliability as this information was not recorded, so these values
may be inflated if applied to intrarater reliability. In addition,
there are the inherent problems when evaluating test–retest reliability including maturation effects, that is, natural changes over
the 2-week period, or testing effects that may have influenced
the data. However, even if these did occur, these effects results
in overestimates of the SEM and MDC, rather than underestimates. Limitations to external validity should also be considered. Although other modified versions of the WMFT have been
developed,21 the original tool was intended to be used with
patients possessing some isolated distal movement capability.
Reservation should be used in the application of these findings
in patients who do not meet the minimal movement criteria
associated with CIMT or in nonstroke patient populations.
Finally, one should highlight the difference between a MDC
and minimal clinically important difference (MCID). An MCID
defines the smallest change that is large enough to make a meaningful difference in patients’ symptomology, functioning, or
quality of life. To establish a minimal clinically important difference (MCID), one would ideally need to relate changes on the
WMFT to changes in an external criterion, such as a validated
measure of quality of life, health care practitioner perception of
recovery,22–24 or the patient’s perspective.25,26 In the absence of
such data, the MDC is sometimes treated as an MCID on the
basis that a starting point for establishing what represents a
minimal clinically meaningful change is a change that is larger
than the testing error. To develop a more rigorous evaluation of
an MCID on the WMFT, determining what might be the amount
of change in the WMFT that would be perceived as beneficial by
the patient is an important area for future consideration.26 The
MDC established in this study does not relate to meaningfulness
of change, simply to measurement error. Even if a patient
exceeds the MDC, this does not mean the change measured is a
meaningful change in function to the patient. This change in the
MDC, however, may begin to offer some guidance to the clinician on whether to justify continuation of care.
The determination of the SEM and MDC of outcome
assessments helps researchers and clinicians to distinguish
actual changes occurring as a result of a therapeutic intervention from chance fluctuations in test scores. The MDC95 for the
overall WMFT timed scores for a cohort of individuals with
sub-acute stroke is 0.7 seconds. This finding means that if an
individual improves by this amount, or more, on the moreaffected extremity average Performance Time, the change is
beyond measurement error and, therefore, likely to represent
an actual change in the underlying construct. Identifying the
absolute reliability of measurement tools in such a manner
assists in interpreting results from clinical research and planning and carrying out clinical treatment.
References
1.Kunkel A, Kopp B, Muller G, et al. Constraint-induced movement therapy
for motor recovery in chronic stroke patients. Arch Phys Med Rehabil.
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