Table 4.

Alternative Model Simulation

Model A – no heterogeneity:
	Affected Sibs		Unaffected Sibs
Parents	Total	Sampled	Total	Sampled	Zc	Zp	ARE(Zc)	ARE(Zp)	Nc(80%)	Np(80%)
0	2	2	2	0	3.19		100		304
0	2	2	2	1	2.70	2.42	72	38	424	528
0	2	2	2	2	3.03	3.17	90	49	337	308
0	3	2	2	0	6.09		364		83
0	3	2	2	1	6.46	6.00	410	236	74	86
0	3	2	2	2	6.12	6.47	368	206	83	74
2	2	2	2		2.88		41		373
2	2	2	2	1	3.17	2.69	49	28	308	427
2	2	2	2	2	3.17	3.33	49	36	308	279
Model B – less common, equally penetrant locus:
0	2	2	2	0	2.37		100		550
0	2	2	2	1	3.04	2.88	165	98	334	373
0	2	2	2	2	2.73	2.81	133	70	415	391
0	3	2	2	0	4.66		387		142
0	3	2	2	1	5.29	5.11	498	310	110	118
0	3	2	2	2	4.86	5.18	421	239	131	115
2	2	2	2	0	2.73		66		415
2	2	2	2	1	2.46	2.22	54	35	511	627
2	2	2	2	2	2.92	2.95	76	52	363	355
Model C – equally common, equally penetrant locus:
0	2	2	2	0	2.38		100		546
0	2	2	2	1	1.93	1.95	66	45	830	813
0	2	2	2	2	2.33	2.36	96	49	569	555
0	3	2	2	0	3.45		210		260
0	3	2	2	1	3.47	3.33	213	131	257	279
0	3	2	2	2	3.48	3.84	214	130	255	210
2	2	2	2	0	2.26		45		605
2	2	2	2	1	2.56	2.44	58	42	472	519
2	2	2	2	2	2.22	2.14	44	27	627	675

Mean Z score, asymptotic relative efficiency per genotype (ARE–see text), and sample size required to attain 80% power for two-point linkage (θ = 0.05) for predisposition to colorectal cancer with a baseline risk of 0.018, a relative risk to carriers of 20, allele frequency of 0.003, with a lifetime penetrance of 0.27, under 3 different heterogeneity models: A) no heterogeneity; B) an equally penetrant, less common (allele frequency 0.001) unlinked predisposing locus; C) an equally penetrant, equally common unlinked predisposing locus. All results based on 500 simulated families and 20 replicate simulations per parameter set.

Z_c mean concordant test; Z_p mean paired test; ARE(Z_c) asymptotic relative efficiency concordant test; ARE(Z_p) asymptotic relative efficiency paired test; Nc(80%) number of families required for 80% power using concordant test; Np(80%) number of families required for 80% power using paired test.