Retrospective design sampling on outcome: compare exposure histories of cases and controls. Estimates odds ratio OR = (a·d)/(b·c) with 2×2 table, a good approximation to the risk ratio for rare outcomes.
Retrospective design sampling on outcome: compare exposure histories of cases and controls. Estimates odds ratio OR = (a·d)/(b·c) with 2×2 table, a good approximation to the risk ratio for rare outcomes.