Validity Evidence for Self-report With Assistance to Measure Physical Activity Behavior in Adults With Intellectual Disabilities

Self-reported physical activity (PA) behavior with assistance from a secondary source has previously been used with adults with an intellectual disability (ID). Limited evidence of reliability and validity have been provided for this approach. This study examined evidence of convergent (CV) and discriminant (DV) validity for self-report with assistance from a secondary source as a measure of PA in adults with ID. PA of 37 participants with ID were assessed using (a) self-report, (b) accelerometers, and (c) pedometers. The multitrait-multimethod (MTMM) analysis was used to evaluate validity. MTMM analysis revealed high reliability among variables, low to strong CV, and moderate DV. The study outcomes provide initial convergent and discriminant validity evidence for this measure of PA in adults with ID.