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Estimating fecundability from data on waiting times to first conception.
Journal of the American Statistical Association
|June 1, 1990
Summary
This study questions standard demographic methods for estimating fecundability, revealing an identification problem in duration models. Conventional goodness-of-fit tests may be unreliable for these population distribution models.
Area of Science:
- Demography
- Biostatistics
- Population Studies
Background:
- Estimating fecundability relies on assumptions about waiting times to conception.
- Continuous time models assume exponential distributions, while discrete time models assume geometric distributions.
Purpose of the Study:
- To test assumptions in demographic literature for estimating fecundability.
- To investigate the identification problem in duration models for conception waiting times.
Main Methods:
- Analysis of waiting times to first conception data.
- Examination of mixture of exponentials and mixture of geometrics distributions.
- Critique of conventional estimation procedures and goodness-of-fit tests.
Main Results:
- The U.S. Hutterite data align with assumed distributions.
- A fundamental identification problem exists in conventional estimation procedures.
- Goodness-of-fit tests may not reliably validate model specifications.
Conclusions:
- The study highlights a critical identification issue in demographic duration models.
- Conventional methods for estimating fecundability may be flawed.
- The practical implications of this identification problem are significant for demographic research.