Construct Validity and Reliability of the Comprehensive Occupational Therapy Evaluation Scale (COTES) in People With Schizophrenia

OBJECTIVE. We evaluated the construct validity (i.e., unidimensionality and convergent validity) and Rasch reliability of the 20-item Comprehensive Occupational Therapy Evaluation Scale (COTES) in people with schizophrenia. METHOD. Retrospective chart review was used to collect COTES data from 505 inpatients with schizophrenia. For construct validity, we first examined unidimensionality of each of the three COTES subscales using Rasch analysis. After unidimensionality was supported, we examined convergent validity using Pearson's r and Rasch reliability of the individual subscales. RESULTS. After deleting two misfitting items, the remaining items (i.e., the COTES-18) showed unidimensionality. Infit and outfit mean squares were 0.73-1.25. Moderate correlations were found among the three COTES-18 subscales (rs =.57-.71). The Rasch reliabilities of the three subscales were.83-.92. CONCLUSION. The COTES-18 has sufficient construct validity and reliability to assess three specific dimensions of behavior affecting occupational performance in people with schizophrenia.