Table 1.

Exposure/Outcome Scenarios for a Study Simulating Clustered-Data Research Settings

Scenario	Pr(Outcome) According to Exposure to X1, X2				Relative Risk			RERI	REOIa	SD in Random Intercepts (${\mathbf{\sigma }}_{\mathit{b}}$)
	Doubly Unexposed (p00)	X1-Exposed (p10)	X2-Exposed (p01)	Doubly Exposed (p11)	RR10b	RR01c	RR11d
1	0.01	0.02	0.03	0.09	2	3	9	5	5.71	0.61
2		0.02	0.03	0.14	2	3	14	10	12.03	0.50
3	0.1	0.1	0.1	0.2	1	1	2	1	1.25	0.40
4		0.2	0.3	0.5	2	3	5	1	3.89	0.17
5		0.1	0.2	0.5	1	2	5	3	6.75	0.17
6	0.2	0.2	0.2	0.4	1	1	2	1	1.67	0.23
7		0.2	0.4	0.6	1	2	3	1	3.33	0.13
8		0.4	0.4	0.8	2	2	4	1	11.67	0.05
9	0.4	0.4	0.4	0.8	1	1	2	1	5.00	0.05
10		0.4	0.4	0.6	1	1	1.5	0.5	1.25	0.13
11	0.6	0.6	0.6	0.9	1	1	1.5	0.5	5.00	0.02

Abbreviations: OR, odds ratio; Pr, probability; REOI, relative excess odds due to interaction; RERI, relative excess risk due to interaction; RR, relative risk; SD, standard deviation.

^a REOI = OR₁₁ − OR₀₁ − OR₁₀ + 1, where OR_ab is the odds ratio comparing the group with exposure X₁ = a and X₂ = b to the doubly unexposed group.

^b RR₁₀, relative risk of the outcome in the group exposed to X₁ and unexposed to X₂ as compared with the doubly unexposed group.

^c RR₀₁, relative risk of the outcome in the group unexposed to X₁ and exposed to X₂ as compared with the doubly unexposed group.

^d RR₁₁, relative risk of the outcome in the doubly exposed group as compared with the doubly unexposed group.