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A comparison of two methods for estimating prevalence ratios.

Authors
Petersen-MR; Deddens-JA
Source
BMC Med Res Methodol 2008 Feb; 8:9
NIOSHTIC No.
20033721
Abstract
Background: it is usually preferable to model and estimate prevalence ratios instead of odds ratios in cross-sectional studies when diseases or injuries are not rare. Problems with existing methods of modeling prevalence ratios include lack of convergence, overestimated standard errors, and extrapolation of simple univariate formulas to multivariable models. We compare two of the newer methods using simulated data and real data from SAS online examples. Methods: the Robust Poisson method, which uses the Poisson distribution and a sandwich variance estimator, is compared to the log-binomial method, which uses the binomial distribution to obtain maximum likelihood estimates, using computer simulations and real data. Results: for very high prevalences and moderate sample size, the Robust Poisson method yields less biased estimates of the prevalence ratios than the log-binomial method. However, for moderate prevalences and moderate sample size, the log-binomial method yields slightly less biased estimates than the Robust Poisson method. In nearly all cases, the log-binomial method yielded slightly higher power and smaller standard errors than the Robust Poisson method. Conclusion: although the Robust Poisson often gives reasonable estimates of the prevalence ratio and is very easy to use, the log-binomial method results in less bias in most common situations, and because it fits the correct model and obtains maximum likelihood estimates, it generally results in slightly higher power, smaller standard errors, and, unlike the Robust Poisson, it always yields estimated prevalences between zero and one.
Keywords
Analytical-methods; Statistical-analysis; Models; Mathematical-models; Risk-analysis
Contact
Martin R Petersen, Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, Mail Stop R15 4676 Columbia Parkway Cincinnati, OH 45226
CODEN
BMRMCG
Publication Date
20080228
Document Type
Journal Article
Email Address
mrp1@cdc.gov
Fiscal Year
2008
NTIS Accession No.
NTIS Price
ISSN
1471-2288
NIOSH Division
DSHEFS
Priority Area
Manufacturing
Source Name
BMC Medical Research Methodology
State
OH
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