Table 1.

Power of haplotype- and cluster-based association analyses at the HLA-DRB1 locus^a

	Powerb
	α = 0.05	α = 0.01	Mean d.f.c
6 Markers d
Haplotypes	0.672	0.379	9.36
Clusters	0.812	0.593	3.65
8 Markers e
Haplotypes	0.654	0.356	10.07
Clusters	0.822	0.597	3.94

^aSex and number of DRB1*04 alleles were included as covariates in all analyses.

^bProportion of 1000 data sets of 150 each cases and controls giving p-values below nominal α.

^cMean degrees of freedom from the score test for association.

^dSNPs 3435–3440.

^eSNPs 3433, 3435–3441.