Traditional methods of developing tests have been driven by item content specification and have relied on the use of summed ordinal scores in an attempt to create a quantitative index of ability. There are fundamental problems with this approach to test development. The first problem is that the summing of qualitative ordinal counts to create a total score does not result in a number that is a valid means of making quantitative comparisons of performances. The second problem is that reliance on content experts does not ensure that the test items indeed test the construct in question. As a result, the development of functional assessments based on Rasch measurement models is becoming a preferred method among rehabilitation professionals for constructing tests. Rasch measurement models offer an alternative approach to instrument development that results in unidimensional linear measures based on additive numbers. Rasch analyses also generate goodness-of-fit statistics that can be used to perform confirmatory construct validity analyses of the constructed scales based on (a) formulating expectations about what should happen when a group of persons take a test, and then (b) confirming that the test items fit that model. This paper describes how the many-faceted Rasch model was used to develop the motor scale of the Assessment of Motor and Process Skills (AMPS) (Fisher, 1992). The process of beginning test development with a theory of expectations related to a constructed scale and then confirming that the scale conforms to these expectations also is demonstrated.

The term occupation conveys the powerful essence of our profession--enabling people to seize, take possession of, or occupy the spaces, time, and roles of their lives. Occupation is activity that is both purposeful and meaningful to the person who engages in it. Our uniqueness lies in our use of occupation as a therapeutic agent, but our unique focus on occupation is not always apparent in practice. Four global groups of activities that occupational therapy practitioners use in practice are described--exercise, contrived occupation, therapeutic occupation, and adaptive occupation. Therapeutic occupation and adaptive occupation are proposed as the legitimate activities of occupational therapy. The Occupational Therapy Intervention Process Model is then presented. This model stresses a top-down approach to evaluation and provides a framework for implementing adaptive occupation for purposes of compensation as well as therapeutic occupation for purposes of remediation.

The author will, therefore, first discuss some key occupational therapy terms and propose that they represent an occupation-related taxonomy that can be used to more clearly define and describe for occupational therapists and others what they do and how they do what they do as occupational therapists. Then, with a goal of fostering critical self-reflection among occupational scientists and occupational therapy researchers, educators, and practitioners, the author will go through the stages of the occupational therapy process outlined in the Occupational Therapy Intervention Process Model (OTIPM) and demonstrate how a more precise use of this occupation-related taxonomy can facilitate maximizing the power of occupation in practice.

The author will, therefore, first discuss some key occupational therapy terms and propose that they represent an occupation-related taxonomy that can be used to more clearly define and describe for occupational therapists and others what they do and how they do what they do as occupational therapists. Then, with a goal of fostering critical self-reflection among occupational scientists and occupational therapy researchers, educators, and practitioners, the author will go through the stages of the occupational therapy process outlined in the Occupational Therapy Intervention Process Model (OTIPM) and demonstrate how a more precise use of this occupation-related taxonomy can facilitate maximizing the power of occupation in practice.