Figure 3
From: Novel study designs to investigate the placebo response
The "delayed response test" (DRT) design: The "additive model" by Kirsch (2000) assumes that P1 = P2. Under the further assumptions that M1 = M2 and P2 = P3, the hypothesis of the "additive model" is falsified if (M1+ P1 ≠M2 + P3).