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Figure 1 | Trials

Figure 1

From: Interaction between drug and placebo effects: a cross-over balanced placebo design trial

Figure 1

Model of drug and placebo effects and their interaction. Total effect is inferred from the difference between received caffeine described as caffeine and received placebo described as placebo. Drug effect is inferred from the difference between received caffeine described as placebo and received placebo described as placebo. The model predicts two kinds of measured "placebo effect": a) PLACEBO-1 is inferred from the difference between received placebo described as caffeine and received placebo described as placebo, which contains the placebo effect only, and b) PLACEBO-2 is inferred from the difference between received caffeine described as caffeine and received caffeine described as placebo, which contains the placebo effect and the interaction effect. Note that PLACEBO-1 is depicted here larger than PLACEBO-2 and that the total effect is smaller than the combination of the drug and placebo effects (as measured by PLACEBO-1) to indicate that the drug and placebo effects are less than additive.

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