Abstract

Doc number: 56

Abstract

Background: In epidemiological studies researchers use logistic regression as an analytical tool to study the association of a binary outcome to a set of possible exposures.

Methods: Using a simulation study we illustrate how the analytically derived bias of odds ratios modelling in logistic regression varies as a function of the sample size.

Results: Logistic regression overestimates odds ratios in studies with small to moderate samples size. The small sample size induced bias is a systematic one, bias away from null. Regression coefficient estimates shifts away from zero, odds ratios from one.

Conclusion: If several small studies are pooled without consideration of the bias introduced by the inherent mathematical properties of the logistic regression model, researchers may be mislead to erroneous interpretation of the results.

Details

Title
Bias in odds ratios by logistic regression modelling and sample size
Author
Nemes, Szilard; Jonasson, Junmei Miao; Genell, Anna; Steineck, Gunnar
Pages
56
Publication year
2009
Publication date
2009
Publisher
Springer Nature B.V.
e-ISSN
14712288
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
1221461174
Copyright
© 2009 Nemes et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.