Covariates

Generally speaking, a covariate is a variable that may impact a dependent variable (other than the previously selected independent variable). A covariate can be controlled for by an analysis of covariance (ANCOVA) or multivariable analysis of covariance (MANCOVA). A real-life example of a study in which a covariate might be included:

Suppose you wanted to know whether or not a certain intervention program had an impact on students' reading ability in grade 2. In this case, the DV is reading ability (as measured by some instrument) and the IV is the intervention. A covariate in this study might be students' reading ability BEFORE placed in the control or treatment group. An ANCOVA could be used to account for this covariate.

Contributed by: Thomas Fox

A covariate is used to adjust post-test scores. For example, when completing an experiment, the treatment group may have higher pretest scores than the control group. A covariate would then be used to adjust the post-test scores due to differences in pretest scores. A covariate is one way to control for extraneous variables (Delcourt, 2013).

Delcourt, M. A. (2013) Lecture: Quantitative research designs II. Retrieved from PBworks: http://ed865fall2013.pbworks.com/w/page/68627608/FrontPage.

contributed by Kara Kunst