Psychometric Properties of the COPM

The COPM is a reliable, valid outcome measure that can be used in a wide variety of clinical settings to help occupational therapists work with clients to set goals and detect change in perceived occupational performance over time.

The COPM is a client-centred, occupation-focused outcome measure.  It uses a semi-structured interview format and structured scoring method.  The COPM measures client-perceived changes in occupational performance over time.

The COPM results in two main scores — PERFORMANCE and SATISFACTION — each out of 10.  PERFORMANCE and SATISFACTION scores can be generated for up to 5 individual occupational performance problems.  Average PERFORMANCE and SATISFACTION scores can be calculated by summing individual problem scores and dividing by the number of problems.

Change scores for both PERFORMANCE and SATISFACTION can be calculated after a reassessment interval.  Since scores for the COPM are dependent on the nature and complexity of problems identified, one person’s score cannot be compared with another.  The only meaningful comparison is an individual’s score changes from Time 1 (assessment) to Time 2 (re-assessment).

The COPM is a standardized instrument in that there are specific instructions and methods for administering and scoring the test.  The COPM is not a norm-referenced measure.  It was not designed to assess deviations in occupational performance from an empirically derived norm.  In fact, no such norm exists, and even if one did, it would be inconsistent with the client-centred approach upon which the COPM is based.

Reliability

As of December 2013, there have been 7 reliability studies published on the COPM.   Internal consistency reliability has been shown to be within a reasonable range.  Test-retest reliability has consistently been found well above the acceptable range.

Validity

Numerous types of validity have been evaluated for the COPM, in various settings and various populations:  content, criterion, convergent, divergent and construct. Sixteen articles were located that examined the validity of the COPM.  These studies consistently supported the validity of the COPM as a measure of occupational performance.

Responsiveness

Responsiveness refers to the ability of the COPM to detect changes in perceived occupational performance over time.  Eight studies showed that the COPM is successful at detecting clinical change.

Utility

Twenty-one studies were found that examined the utility of the COPM.  In all instances, the COPM was found to offer significant benefits in a wide variety of clinical settings, with different populations, and in different languages and cultures.  Mean administration time for the COPM has been found to be 20–40 minutes.  Therapists report that the COPM help therapists work more holistically, and also helps to clarify the OT role for team members and clients.

For specific details of psychometric evaluation, please consult the manual of the 5th edition of the COPM. Purchase the COPM.

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