Motivated by the need from our on-going environmental study in the Norwegian Mother and Child Cohort (MoBa) study, we consider an outcome-dependent sampling (ODS) scheme for failure-time data with censoring. Like the case-cohort design, the ODS design enriches the observed sample by selectively including certain failure subjects. We present an estimated maximum semiparametric empirical likelihood estimation (EMSELE) under the proportional hazards model framework. The asymptotic properties of the proposed estimator were derived. Simulation studies were conducted to evaluate the small-sample performance of our proposed method. Our analyses show that the proposed estimator and design is more efficient than the current default approach and other competing approaches. Applying the proposed approach with the data set from the MoBa study, we found a significant effect of an environmental contaminant on fecundability.
Notes
Cites: Hum Reprod. 2009 May;24(5):1200-519176540
Cites: Biometrics. 2007 Dec;63(4):1288-9517608788
Cites: Biometrics. 2002 Jun;58(2):413-2112071415
Cites: Med J Aust. 1972 Sep 23;2(13):714-85084969
Cites: J Natl Cancer Inst. 1951 Jun;11(6):1269-7514861651