Affiliation:
1. Department of Epidemiology and Biostatistics, Indiana University School of Public Health-Bloomington
2. Department of Applied Health Science, Indiana University School of Public Health-Bloomington
3. Department of Statistics and Data Science, Southern Methodist University
4. University of Memphis, School of Public Health
Abstract
We discuss 12 misperceptions, misstatements, or mistakes concerning the use of covariates in observational or nonrandomized research. Additionally, we offer advice to help investigators, editors, reviewers, and readers make more informed decisions about conducting and interpreting research where the influence of covariates may be at issue. We primarily address misperceptions in the context of statistical management of the covariates through various forms of modeling, although we also emphasize design and model or variable selection. Other approaches to addressing the effects of covariates, including matching, have logical extensions from what we discuss here but are not dwelled upon heavily. The misperceptions, misstatements, or mistakes we discuss include accurate representation of covariates, effects of measurement error, overreliance on covariate categorization, underestimation of power loss when controlling for covariates, misinterpretation of significance in statistical models, and misconceptions about confounding variables, selecting on a collider, and p value interpretations in covariate-inclusive analyses. This condensed overview serves to correct common errors and improve research quality in general and in nutrition research specifically.
Funder
National Institutes of Health
Publisher
eLife Sciences Publications, Ltd
Reference132 articles.
1. Twenty-five years of research about adipogenic adenoviruses: a systematic review;Akheruzzaman;Obesity Reviews,2019
2. Some of the most common questions asked of statistical consultants: Our favorite responses and recommended readings;Allison;Genetic, Social, and General Psychology Monographs,1993
3. When is it worth measuring a covariate in a randomized clinical trial?;Allison;Journal of Consulting and Clinical Psychology,1995
4. Power and money: designing statistically powerful studies while minimizing financial costs;Allison;Psychological Methods,1997
5. Quartiles, quintiles, centiles, and other quantiles;Altman;BMJ,1994