Reliability and validity of Turkish form of Endicott Work Productivity Scale

OBJECTIVE: The Endicott Work Productivity Scale (EWPS) is a brief self-report questionnaire designed to enable investigators to obtain a sensitive measure of work productivity. The purpose of the study was to investigate reliability and validity of the Turkish form of EWPS. METHOD: The study was performed with two separate groups; a patient group (n=74) and a community sample (n=107). Through the adaptation process the original form was translated into Turkish, and translated back into English. Statistical tests about construct validity, the concurrent validity, the test re-test reliability and internal consistency were performed. RESULTS: The internal consistency coefficient (Cronbach's alpha) was >.90 for both groups. The correlations of the individual items with the EWPS total scores ranged between.32 and.75. EWPS and HAM-D scores of the patient group was positively correlated (r =.52 and r =.62). The CGI scores correlation was.64 and SF-36 social functioning subscale was correlated negatively (r= -.43). The correlations of the test-retest scores of EWPS were.76. There was a significant mean difference between the total scores of patient and the community groups. CONCLUSION: The Turkish form of EWPS was found to be valid and reliable. The findings concerning the reliability and the validity of the EWPS indicate that this instrument can be used in the studies that will be conducted in Turkey.