title: Estimating effect of environmental contaminants on women's subfecundity for the MoBa study data with an outcome-dependent sampling scheme.
abstract: 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.
authors.affiliation: School of Mathematics and Statistics, Wuhan University, Wuhan, Hubei 430072, China.
authors.forename: Jieli
authors.initials: J
authors.lastname: Ding
authors.affiliation: Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA zhou@bios.unc.edu.
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhou
authors.affiliation: School of Mathematics and Statistics, Wuhan University, Wuhan, Hubei 430072, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Jianwen
authors.initials: J
authors.lastname: Cai
authors.affiliation: National Institute of Environmental Health Sciences, National Institute of Health, Research Triangle Park, NC 27709, USA.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Longnecker
mesh_terms: D000328:Adult; D002210:Caprylates / Q000009:adverse effects*; D015331:Cohort Studies; D004781:Environmental Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D004785:Environmental Pollutants / Q000009:adverse effects*; D005260:Female; D005298:Fertility / Q000187:drug effects*; D005466:Fluorocarbons / Q000009:adverse effects*; D006801:Humans; D016013:Likelihood Functions; D009664:Norway / Q000453:epidemiology; D011247:Pregnancy; D016016:Proportional Hazards Models
chemical_list: D002210:Caprylates; D004785:Environmental Pollutants; D005466:Fluorocarbons; C023036:perfluorooctanoic acid
keywords: Biased-sampling; Empirical likelihood; Proportional hazards model; Survival analysis