Dale Dale Bikin, Pharm.
Analysis of covariance is a combination of regression analysis with an analysis of variance.
In the following example, by virtue of a linear relationhip with Kel, CrCl serves as a covariate in several treatment groups studing the effect of the treatments on Kel. A random effect of the jth element in the ith treatment group. By examination of the variances in the Kel in the various treatment groups when corrected for the variance caused by the linear relationship between CrCl and Kel, analysis of covariance will find if there is any significant effect of the various treatments on Kel. If the null hypothesis is not rejected, than the regression equation for Kel and creatinine clearance explains the variances in the Kel observed among the various treatment groups. If the null hypthesis is rejected, than a separate regression equation for each treatment group should be considered.