The Lipid Research Clinics Coronary Primary Prevention Trial (LRC-CPPT) measured the effectiveness of the drug cholestyramine for lowering cholesterol levels. The patients in the study were measured for compliance (the proportion of the intended dose actually taken) and for cholesterol decrease. The compliance-response regression for the Treatment group shows a smooth increasing effect of the drug in cholesterol level with increasing compliance. However, a similar, though less dramatic, compliance-response regression is seen in the Control group. This article investigates the recovery of the true dose-response curve from the Treatment and Control compliance-response curves. A simple model is proposed, analyzed, and applied to the LRC-CPPT data. Under this model, part but not all of the true dose-response curve can be estimated.