Note. Evaluating exclusionary interventions.
In evaluation research, some interventions are designed to affect both the subjects that receive the intervention and those that do not. Preferred provider organizations (PPOs) are an example, because if they are successful, PPOs will direct patients away from non-preferred providers towards preferred providers. When the intervention affects all subjects, the excluded group cannot serve as a control group if one wishes to estimate the experience of subjects in the absence of the intervention. That estimate must come from subjects completely unaffected by the treatment.
Dowd
B
B
Division of Health Services Research and Policy, School of Public Health, University of Minnesota, Minneapolis 55455.
Feldman
R
R
D003284:Contract Services / Q000191:economics / Q000706:statistics & numerical data; D005069:Evaluation Studies as Topic; D006302:Health Services Research / Q000379:methods*; D015273:Insurance Selection Bias; D017063:Outcome Assessment, Health Care / Q000379:methods; D010342:Patient Acceptance of Health Care; D011243:Preferred Provider Organizations / Q000191:economics* / Q000706:statistics & numerical data; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D014481:United States