. 2004 Aug 20;75(4):571–586. doi: 10.1086/424528

Table 4.

Results of Power Calculations Performed on Sibships of Various Size^[Note]

	Value for Total Sibship Size
	3 Total, 2 Affected (80^b)		4 Total, 2 Affected (67^b)		4 Total, 3 Affected (83^b)		5 Total, 3 Affected (71^b)
Model, Penetrances for Genotypes, K_S (%),and Marker^a	N_ad	N_ad:N_pairs^c	N_ad	N_ad:N_pairs^c	N_ad	N_ad:N_pairs^c	N_ad	N_ad:N_pairs^c
Recessive (q = .316):
DD = .08, Dd = .08, dd = .78, K_S = 25.9:
M₁	61	.68	55	.6	26	.87	17	.65
M₂	92	.68	81	.58	38	.86	25	.66
DD = .10, Dd = .10, dd = .60, K_S = 20.5:
M₁	199	.78	183	.65	74	1	54	.78
M₂	299	.78	269	.66	111	1.03	78	.79
DD = .12, Dd = .12, dd = .40, K_S = 16.7:
M₁	1,756	.83	1,609	.73	533	1.18	416	.93
M₂	2,819	.81	2,430	.72	801	1.2	640	.92
DD = .13, Dd = .13, dd = .33, K_S = 15.9:
M₁	6,302	.96	5,788	.72	1,973	1.28	1,591	.95
M₂	9,640	.97	8,365	.72	2,983	1.3	2,341	.93
Dominant (q = .0513):
DD = .08, Dd = .78, dd = .78, K_S = 29.5:
M₁	68	.5	67	.42	26	.68	18	.51
M₂	102	.5	98	.42	38	.66	27	.51
DD = .10, Dd = .60, dd = .60, K_S = 22.4:
M₁	230	.66	213	.56	68	.87	52	.66
M₂	344	.66	328	.57	99	.86	76	.64
DD = .12, Dd = .40, dd = .40, K_S = 17.3:
M₁	1,672	.75	1,708	.67	448	1.12	387	.82
M₂	2,622	.72	2,436	.65	657	1.11	584	.82
DD = .13, Dd = .33, dd = .33, K_S = 16.2:
M₁	5,854	.87	6,012	.73	1,563	1.18	1314	.93
M₂	9,848	.89	8,863	.74	2,234	1.14	1,987	.93
Additive (q = .1):
DD = .08, Dd = .43, dd = .78, K_S = 22.4:
M₁	241	.78	193	.67	98	.98	70	.77
M₂	360	.78	276	.66	144	.99	100	.76
DD = .10, Dd = .35, dd = .60, K_S = 18.8:
M₁	743	.82	635	.72	273	1.13	211	.85
M₂	1,095	.82	923	.73	406	1.13	305	.82
DD = .12, Dd = .26, dd = .40, K_S = 16.1:
M₁	6,534	.94	6,316	.79	1,873	1.22	1,585	.94
M₂	9,760	.92	9,524	.8	2,756	1.26	2,350	.94
DD = .13, Dd = .23, dd = .33, K_S = 15.6:
M₁	21,369	.9	20,561	.85	8,562	1.32	5,163	.91
M₂	40,511	.88	38,026	.92	13,052	1.28	8,387	.94

Note.— Parental genotypes are available. The nominal type I error is 0.1%. Parameters are estimated from at least 50,000 simulated replicates.

Penetrances are given in terms of the genotypes at the disease locus, where d is the susceptibility allele, with frequency q. K_S is the sibling recurrence risk for the disease model. In all cases, the disease prevalence is 15%.

Percentage of individuals used by S_pairs.

Ratio N_ad:N_pairs of the required number of pedigrees of a single type to achieve a power of 80% for the S_ad statistic (N_ad) and the S_pairs statistic (N_pairs), calculated at marker M₁ and marker M₂.