Table 1.

Type I Error Rate from Analysis with No Adjustment, Global-Ancestry Adjustment, and Local-Ancestry Adjustment for Population Structure

Effect Size Percentile	Stratification Source (Effect Size)	No Adjustment	GA Adjustment	LA Adjustment
(100% percentile)	GA (57.47)	2.75 × 10−4	9.79 × 10−5	1.10 × 10−4
	LA (1.13)	1.07 × 10−2	4.12 × 10−3	1.03 × 10−4
(75% percentile)	GA (22.43)	1.20 × 10−4	1.02 × 10−4	1.00 × 10−4
	LA (0.27)	2.00 × 10−4	1.50 × 10−4	1.04 × 10−4
(50% percentile)	GA (13.40)	1.05 × 10−4	9.85 × 10-5	9.83 × 10−5
	LA (0.16)	1.30 × 10−4	1.19 × 10−4	1.01 × 10−4
(25% percentile)	GA (6.71)	1.03 × 10−4	9.84 × 10−5	1.01 × 10−4
	LA (0.07)	1.07 × 10−4	1.03 × 10−4	9.84 × 10−5

False positives were identified by using p < 1 × 10⁻⁴. GA stands for global ancestry and LA stands for local ancestry.