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Bias in indirectly adjusted comparisons due to taking the total study population as the reference group
Author(s) -
Greenland Sander
Publication year - 1987
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.4780060211
Subject(s) - covariate , statistics , multiplicative function , referent , econometrics , population , mathematics , medicine , environmental health , mathematical analysis , philosophy , linguistics
It is well known that comparisons of indirectly adjusted statistics, such as standardized morbidity ratios (SMRs), can be biased when the joint effect of the study exposure and thecovariates is not multiplicative. This paper describes a related bias in SMR comparisons, one that can arise if the total study population is used as the referent. This bias can occur even if the exposure‐covariate effects are multiplicative.