How to design an effective treatment outcome study

This paper provides a "how to" guide for designing an effective treatment outcome study. Three areas addressed are (1) a description of the three stages: treatment development, efficacy testing, and effectiveness testing; (2) suggestions for writing a grant proposal; and (3) optimal study design. The latter includes considerations of comorbidity, standard design features, treatment, assessment, patients, therapists, and replication. These are discussed with regard to the testing of psychosocial treatments, with examples from the area of pathological gambling. Finally, general questions applicable to any study are provided, including: Is there a rationale for all design decisions? Is the investigator aware of what can and cannot be inferred from the data, based on the design? Does the study design address research questions that are important and genuinely of benefit to the field?