Table 2.

Computed sample size, estimated power, and simulated power for Normal predictors with {β_I, β_S} = {0.3, 1.3}, {β_I0, β_S0} = {0, 1}, σ² = 1, Type I error α = 0.05, and nominal power 1 – β = 0.90

μX	${\sigma }_X^2$	N	Simulated power	Exact approach		Approximate method
				Simulated power	Error	Simulated power	Error
0	0.5	99	0.9049	0.9025	−0.0024	0.7524	−0.1525
	1	76	0.8997	0.9030	0.0033	0.6257	−0.2740
	2	53	0.9058	0.9050	−0.0008	0.4602	−0.4456
0.5	0.5	56	0.9029	0.9055	0.0026	0.8430	−0.0599
	1	48	0.8993	0.9024	0.0031	0.7756	−0.1237
	2	38	0.8997	0.9006	0.0009	0.6604	−0.2393
1	0.5	35	0.9015	0.9013	−0.0002	0.8682	−0.0333
	1	33	0.9075	0.9089	0.0014	0.8445	−0.0630
	2	28	0.8993	0.9016	0.0023	0.7689	−0.1304