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

Variables are constructs (an idea that is conceived by observing a phenomenon or phenomena). A covariate is a special type of variable that may reveal the relationships between dependent and independent variables. A research design may include a covariate and have it function to mitigate between the dependent and independent variables. With this, the data obtained helps the researcher nuance the data that is to be evaluated.

contributed by Héctor Huertas

A covariate could be 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 posttest Bold textscores 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