Table 1.

Type I error for the unrelated-case (UC) and affected sibpair (AS) designs.

No of unrelated cases/No of sibpairs at stage 1	300/150		400/200		600/300		800/400		1000/500
Significance level	0.05	0.01	0.05	0.01	0.05	0.01	0.05	0.01	0.05	0.01
Phase known
UC	0.039	0.009	0.04	0.004	0.04	0.006	0.048	0.01	0.047	0.011
AS	0.047	0.02	0.046	0.012	0.044	0.01	0.055	0.009	0.048	0.009
Phase unknown
UC	0.053	0.009	0.053	0.014	0.052	0.008	0.049	0.007	0.046	0.012
AS	0.052	0.013	0.067	0.011	0.051	0.011	0.055	0.013	0.056	0.015