Document Detail


Modelling digit preference in fecundability studies.
MedLine Citation:
PMID:  1786326     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Retrospective studies of fecundability, in which women are asked how many cycles they required to become pregnant, are often affected by problems of digit preference. A probability model for such digit preference is proposed in which misreporting favours 6 or 12 (and possibly also 3) cycles. It is assumed that in the absence of misreporting the number of cycles follows a beta-geometric distribution. The model is applied to two data sets, with clear-cut results: The inclusion of additional parameters to model the misreporting can lead to substantial improvements in fit, but causes little change to the estimated parameters of the underlying beta-geometric distribution. In some cases misreporting parameters may be regarded as nuisance parameters, while in others they may be of interest. We have found estimates of these parameters to vary between different categories of women in an interpretable manner. The models may also be used to estimate the percentage of couples in any study that misreport their conception waiting time.
Retrospective studies of fecundability, in which women are asked how many menstrual cycles were required for them to become pregnant, are often affected by problems of digit preference. A probability model for such digit preference is proposed in which misreporting favors 6 or 12 (and possibly also 3) cycles. It is assumed that in the absence of misreporting, the number of cycles follows a beta-geometric distribution. The model is applied to 2 data sets, with clearcut results. The inclusion of additional parameters to model the misreporting can lead to substantial improvements in fit, but causes little change to the estimated parameters of the underlying beta-geometric distribution. In some cases, misreporting parameters may be regarded as nuisance parameters, but in others they may be of some interest. The authors have found estimates of these parameters to vary between different categories of women in an interpretable manner. The models may also be used to estimate the % of couples in any study who misreport their conception waiting time. (author's modified)
Authors:
M S Ridout; B J Morgan
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Biometrics     Volume:  47     ISSN:  0006-341X     ISO Abbreviation:  Biometrics     Publication Date:  1991 Dec 
Date Detail:
Created Date:  1992-03-20     Completed Date:  1992-03-20     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0370625     Medline TA:  Biometrics     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1423-33     Citation Subset:  IM; J    
Affiliation:
Institute of Horticultural Research, Maidstone, Kent, England.
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MeSH Terms
Descriptor/Qualifier:
Biometry
Contraception
Female
Fertility*
Humans
Menstrual Cycle
Models, Biological*
Models, Statistical
Pregnancy

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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