This book discusses various methods to correct for the influence of a covariate on a response variable. First, the use of ratios is dismissed with the reasons for its inappropriateness and some references. The rest of the book compares ANOVA on residuals and ANCOVA. It is demonstrated that ANOVA on residuals is only appropriate when the regression lines are parallel and covariate means are equal for all treatments. The assumptions of normality and HOV, sample size, and clustering of the covariates are manipulated in the simulations. Both methods exhibited similar size and power...