Table 2.

Type I Error Rates for Tests of Interaction^a

% of Families With a Parent's Genotype Missing	Population Allele and Exposure Frequencies
	Allele frequency in population 1:	0.1	0.2	0.3	0.4	0.5
	Allele frequency in population 2:	0.9	0.8	0.7	0.6	0.5
	Frequency with E = 0 in population 1:	0.9	0.8	0.7	0.6	0.5
	Frequency with E = 0 in population 2:	0.1	0.2	0.3	0.4	0.5
0	QPL with 2 df	0.098	0.054	0.051	0.059	0.061
	QTDT with 2 df	0.05	0.04	0.05	0.06	0.05
	Case-control with 2 df	1	1	0.93	0.151	0.057
	Case-only with 2 df	1	0.999	0.626	0.101	0.061
	QPL with 1 df	0.05	0.047	0.054	0.056	0.054
	FBAT-I (1 df)	0.045	0.044	0.049	0.054	0.054
	QTDT with 1 df	0.04	0.04	0.05	0.06	0.05
	Case-control with 1 df	1	1	0.96	0.192	0.053
25	QPL with 2 df	0.108	0.059	0.052	0.061	0.063
	QPL with 1 df	0.053	0.041	0.057	0.056	0.063

Abbreviations: FBAT-I, family-based association test with interaction; QPL, quantitative polytomous logistic; QTDT, quantitative transmission disequilibrium test.

^aResults are based on 1,000 simulations for each scenario of studies in a population subject to population stratification but with no interaction (rightmost column has no population stratification).