Figure 3

The impact of baseline risk (R ₀₀ and interaction magnitude on the discrepancy between the synergy index calculated using risk ratios (S) and that calculated using odds ratios (SF). Each curve represents a specific value of S and changes on the vertical scale represent the magnitude of the discrepancy. Interaction scenarios: Less than additive; S = -0.25 and 0.25; Exactly additive: S = 1; More than additive and less than multiplicative S = 1.25.; Exactly multiplicative: S = 1.5; More than additive and more than multiplicative: S = 2 and 3 (These correspond to the ICR values depicted in Figure 1).