Using Non-Experimental Data to Estimate Treatment Effects

Abstract

Although much psychiatric research is based on randomized controlled trials (RCTs), where patients are randomly assigned to treatments, sometimes RCTs are not ethical nor feasible. Ethical concerns might preclude randomization, such as when evaluating whether “light cigarettes” produce less health risk by potentially randomizing subjects to smoke different brands, or it may be impractical, such as when the treatment of interest is widely available and commonly used. When RCTs are unethical or infeasible, a carefully constructed nonexperimental study can often be used to estimate treatment effects. Although nonexperimental studies are disadvantaged by lack of randomization, the study costs may be lower, the study sample may be broader, and follow-up may be longer, as compared to an RCT.