RT Book, Section A1 Portney, Leslie G. SR Print(0) ID 1187147652 T1 Principles of Clinical Trials T2 Foundations of Clinical Research: Applications to Evidence-Based Practice, 4e YR 2020 FD 2020 PB F. A. Davis Company PP New York, NY SN 9780803661134 LK fadavispt.mhmedical.com/content.aspx?aid=1187147652 RD 2024/03/28 AB A clinical trial is a study designed to test hypotheses about comparative effects. Trials are based on experimental designs, within which the investigator systematically introduces changes into natural phenomena and then observes the consequences of those changes. The randomized controlled trial (RCT) is the standard explanatory design, intended to support a cause-and-effect relationship between an intervention (the independent variable) and an observed response or outcome (the dependent variable).