Development of the DPA Fidelity Scale: using fidelity to define an existing vocational model.

Psychiatric rehabilitation practices are often poorly defined, hindering implementation, research, and dissemination efforts. Documentation of adherence to a specific psychiatric rehabilitation approach is particularly important in conducting randomized controlled trials. This paper outlines steps taken to define and measure the Diversified Placement Approach (DPA), a well-regarded vocational program for people with severe mental illnesses. Details of scale development are described, and the scale's utility for model clarification and detection of experimental drift are discussed.