Drugs are typically brought to market based on the results of randomized clinical trials (RCTs). In their simplest construction, 1 group of patients receives the new drug while another receives something else—usually placebo or another therapy. If the 2 groups of patients are similar at baseline, any differences in outcome (positive or negative) can be reasonably attributed to the drug being tested. The appeal of RCTs rests in their simplicity, and avoidance of biases and confounding. Randomized clinical trials are generally the best way to establish the risks and benefits of a therapeutic intervention for a particular group of patients.