has_specified_input achieves_planned_objective study design independent variable study design dependent variable data transformation ANCOVA 1 1 Orlaith Burke ANCOVA or analysis of covariance is a data transformation which evaluates if population means of a dependent variable are equal across levels of a categorical independent variables while controlling for the effects of other continuous variable s, known as covariates. Therefore, when performing ANCOVA, we are adjusting the dependent variable means to what they would be if all groups were equal on the covariates. It augments the ANOVA model with one or more additional quantitative variables, called covariates, which are related to the response variable. The covariates are included to reduce the variance in the error terms and provide more precise measurement of the treatment effects. ANCOVA is used to test the main and interaction effects of the factors, while controlling for the effects of the covariate Alejandra Gonzalez-Beltran Philippe Rocca-Serra adapted from wikipedia continuous variable categorical variable between group comparison objective between group comparison statistical test ready for release