Table 7.

Number of sib pairs required to detect spurious (H1:B = W vs. H0: B≠W) and genuine (H1:B≠W = 0 vs. H0: B≠W≠0) G × E interaction effects in eight different conditions for power of .80 with α = .05^a

	Dichotomous environment		Continuous environment
	B = W	B≠W = 0	B = W	B≠W = 0
Design(i)	4,745	274	2,543	184
Design(i = c)	4,129	192	3,277	126
Design(i,e)	3,832	274	4,000	184
Design(i,a)	3,470	274	2,071	184
Design(i,a,d)	3,658	274	2,146	184
Design(i,a,e)	2,914	274	3,045	184
Design(−i,a)	6,922	274	3,235	184
Design(−i,a,e)	5,318	274	5,563	184

B = W, test for presence of population stratification; B≠W = 0, test for significance of within-family interaction effect only

^aAll tests assume two degrees of freedom