The main purpose of this study was to estimate the minimal detectable change (MDC) on the Lawton Instrumental Activities of Daily Living (LIADL) scale in community-dwelling patients with schizophrenia. Fifty-seven patients completed the LIADL assessment twice, about 14 days apart. Two scoring methods (dichotomous and polytomous) were used to record the patients' performance on the LIADL scale. The MDCs of the LIADL scale were 1.5 (dichotomous) and 4.4 (polytomous) points. The MDC percentages were 22.0% (dichotomous) and 22.5% (polytomous), both of which are within acceptable measurement errors. The test-retest reliabilities of the LIADL scale were both acceptable with two different scoring methods (dichotomous = .75; polytomous = .76). Users can choose the scoring method according to their individual needs.
Research on the LIADL scale with 57 community-dwelling patients with schizophrenia confirmed the validity of the MDC score for both dichotomous and polytomous scoring.