Tufts assessment of motor performance: an empirical approach to identifying motor performance categories

The Tufts Assessment of Motor Performance (TAMP) is a criterion-referenced test that measures motor performance capabilities of basic self-care skills, mobility and physical aspects of communication. Discrete motor performance tasks were identified within each of the 32 items. The purpose of this paper is to report the results of an empirical method of determining the factor structure underlying the motor performance tasks of the TAMP. Initially, motor performance tasks were categorized into a priori groupings based on previous literature and clinical judgment. The TAMP was administered to 206 children and adults (age range 6 to 86 years) with physical disabilities. Diagnoses included a variety of musculoskeletal and neurologic disorders. A principal-factor analysis was used to organize and cluster the item tasks into appropriate common factors. Seven factors were identified that accounted for 70.6% of the total variance for the assistance dimension; similar results were obtained for other measurement dimensions of the TAMP. The defined factor structure has patterns of similarity to the motor performance variables as defined by clinical judgment; however, the tasks were organized into factors that were more functionally oriented than expected. The results provide a framework for which the motor performance tasks of the TAMP might be organized into scales that identify essential performance constructs for rehabilitation. The results permit examination of the nature and clinical importance of these common motor performance factors for clinical evaluation and the description of functional disability.