Off-campus Pacific University users: To download campus access theses and dissertations, please log into our proxy server with your PUNet ID and password.

Non-Pacific University users: Please talk to your librarian about requesting this thesis or dissertation through interlibrary loan.

Theses or dissertations that have a specific embargo period indicated below will not be available to anyone until the date indicated.

Date of Award


Degree Type

Dissertation (On-Campus Access Only)

Degree Name

Doctor of Psychology (PsyD)

Committee Chair

Paula Truax

Second Advisor

Johan Rosqvist

Third Advisor

Michel Hersen


Both wait-list and placebo control groups represent a homogenous problem in conducting effectiveness research. Each is considered a methodological necessity, while at the same time being viewed as an ethically undesirable aspect of research. The present study attempts to satisfy both the ethical requirement to treat research subjects humanely and the rigors of scientific methodology. Effect sizes were calculated for wait-list and pill placebo controlled anxiety outcome studies. Data were analyzed from 36 studies including 1,439 unique subjects in an attempt to establish the improvement or deterioration of individuals in control conditions of anxiety treatment research. Data analyses determined subjects in anxiety outcome research assigned to the wait-list control condition demonstrated very little improvement regardless of anxiety diagnosis or time in the control condition. Data analyses also determined that subjects in the pill placebo control condition demonstrated significant improvement, with the greatest improvement during the first six weeks of the placebo condition. Further, the current study established posttraumatic stress disorder as the most responsive (i.e., demonstrated the greatest improvement) diagnosis, and obsessive-compulsive disorder as the disorder demonstrated the least improvement regardless of control condition