Discordant Pairs
Case-control pairs in which the case was exposed and the control was not ('b' cell in a 2×2), or pairs in which the control was exposed and the case was not ('d' cell in a 2×2).
Case-control pairs in which the case was exposed and the control was not ('b' cell in a 2×2), or pairs in which the control was exposed and the case was not ('d' cell in a 2×2).