Reliability and validity of the work assessment scale for persons with multiple sclerosis.

Reliability and validity of the Work Assessment Scale (WAS) was done on a sample of 551 subjects with multiple sclerosis. Work was defined as those activities performed in employment, homemaking and/or personal care. The WAS has two parts consisting of: Work-Impeding (WAS-I) and Work Enhancing (WAS-E) situations and conditions. Varimax rotated factor analysis of the WAS-I resulted in a seven-factor solution containing 33 of the 53 scale items. Theta reliability coefficients for the factors ranged between .73 and .90 and test-retest correlation coefficients (n = 51) ranged between .76 and .91. Varimax rotated factor analysis of the WAS-E resulted in a five-factor solution containing 19 of the 27 scale items. Theta reliability coefficients for the factors ranged between .66 and .81 and test-retest correlation coefficients ranged between .68 and .82. Concurrent validity was shown between WAS and both ADL and Symptom subscales.