Inflation of the type I error rate when a continuous confounding variable is categorized in logistic regression analyses.

@article{citeulike:1529741, abstract = {This paper demonstrates an inflation of the type I error rate that occurs when testing the statistical significance of a continuous risk factor after adjusting for a correlated continuous confounding variable that has been divided into a categorical variable. We used Monte Carlo simulation methods to assess the inflation of the type I error rate when testing the statistical significance of a risk factor after adjusting for a continuous confounding variable that has been divided into categories. We found that the inflation of the type I error rate increases with increasing sample size, as the correlation between the risk factor and the confounding variable increases, and with a decrease in the number of categories into which the confounder is divided. Even when the confounder is divided in a five-level categorical variable, the inflation of the type I error rate remained high when both the sample size and the correlation between the risk factor and the confounder were high.}, address = {Institute for Clinical Evaluative Sciences, Toronto, Canada. peter.austin@ices.on.ca}, author = {Austin, P. C. and Brunner, L. J. }, citeulike-article-id = {1529741}, doi = {10.1002/sim.1687}, issn = {0277-6715}, journal = {Stat Med}, month = {April}, number = {7}, pages = {1159--1178}, posted-at = {2007-08-02 06:57:11}, priority = {2}, title = {Inflation of the type I error rate when a continuous confounding variable is categorized in logistic regression analyses.}, url = {http://dx.doi.org/10.1002/sim.1687}, volume = {23}, year = {2004} }

TY - JOUR ID - citeulike:1529741 L3 - citeulike-article-id:1529741 TI - Inflation of the type I error rate when a continuous confounding variable is categorized in logistic regression analyses. JF - Stat Med VL - 23 IS - 7 SP - 1159 EP - 1178 AD - Institute for Clinical Evaluative Sciences, Toronto, Canada. peter.austin@ices.on.ca SN - 0277-6715 N2 - This paper demonstrates an inflation of the type I error rate that occurs when testing the statistical significance of a continuous risk factor after adjusting for a correlated continuous confounding variable that has been divided into a categorical variable. We used Monte Carlo simulation methods to assess the inflation of the type I error rate when testing the statistical significance of a risk factor after adjusting for a continuous confounding variable that has been divided into categories. We found that the inflation of the type I error rate increases with increasing sample size, as the correlation between the risk factor and the confounding variable increases, and with a decrease in the number of categories into which the confounder is divided. Even when the confounder is divided in a five-level categorical variable, the inflation of the type I error rate remained high when both the sample size and the correlation between the risk factor and the confounder were high. AU - Austin, PC AU - Brunner, LJ PY - 2004/04/15/ UR - http://dx.doi.org/10.1002/sim.1687 ER -