In nested case-control studies the controls are sampled from the risk set at the failure times of the cases. The analytical basis for such studies has been limited to semiparametric estimators under ...

Larry Goldstein, Bryan Langholz, Asymptotic Theory for Nested Case-Control Sampling in the Cox Regression Model, The Annals of Statistics, Vol. 20, No. 4 (Dec., 1992), pp. 1903-1928 ...