<qa>  What is the randomized controlled trial to evaluate?This study will examine placebo responses in the context of practitioner-patient interactions at the time of the encounter. Phase 1 of this study identified patient-related determinants of placebo response, such as beliefs and expectations toward treatment of knee OA with acupuncture. Phase 2 of the study evaluated an assessment tool to measure these determinants. Phase 3 of the study is a randomized controlled trial to evaluate whether placebo effects in patients with knee OA can be enhanced by the acupuncturists communicative style, which can affect a patients cognitive expectancies and beliefs. 