by the axis with the largest genetic variation. When the controls were exchanged between the two studies, the procedure required the 1st, 2nd, and 4th PCs in PLCOca-NHSco, and the 1st, 2nd, and 3rd PCs in NHSca-PLCOco. Thus, the increased heterogeneity between cases and controls created in the two reconstructed studies resulted in the inclusion of two additional PCs in order to sufficiently correct for the confounding effect.
