Estimating Fecundability From Data on Waiting Times to First Conception
检验了人口学中从首次受孕等待时间估计生育力分布的关键假设，发现传统估计方法存在根本性的识别问题，并质疑了仅用拟合优度检验验证模型的做法。
Abstract This article tests assumptions invoked in the demographic literature to estimate the population distribution of fecundability from data on waiting times to first conception. In continuous time, the key assumption is that waiting times are realizations from a mixture of exponentials distribution. In discrete time, the key assumption is that waiting times are realizations from a mixture of geometrics distribution. The Hutterite data analyzed by Sheps (1965) are consistent with this assumption. Various models, however, have one representation in mixture of exponentials form. A fundamental identification problem plagues the conventional estimation procedure. Our analysis calls into question the conventional practice of checking model specification by using goodness-of-fit tests. The practical importance of the identification problem in duration models is demonstrated.