We derive second-order expressions for the asymptotic bias and variance of the log relative incidence estimator for the self-controlled case series method in a simplified scenario, and study in qualitative terms how bias and variance depend on factors such as the relative incidence and ratio of risk to observation period. Small-sample performance of the estimator in realistic scenarios is investigated using simulations. We find that in scenarios likely to arise in practice, asymptotic methods are valid for numbers of cases in excess of 20
Patrick Musonda, Mounia N. Hocine, Heather J. Whit