The change-in-estimate method (CIE) is a well established method for selecting confounding variables to include in a regression model. Confounders bias estimates of exposure effect and, in short, to identify a confounder (C) we calculate two estimates of the effect of exposure on the outcome, one which is adjusted for the C and the other we don't. If the two estimates differ, we conclude that C is in fact a confounder. The function dropCIE.R was developed to use with the glm