What does covariate mean?
In modern English, a covariate is a secondary variable used in a statistical model to help describe, predict, or adjust for variation in the main variable of interest. For example, a study of lung disease might consider age, smoking history, and occupational exposure as covariates while examining the effect of air pollution. A covariate need not cause the outcome, and a variable may serve as a covariate in one analysis but as the principal subject of another. The adjective form appears in expressions such as “covariate adjustment” and “covariate information.” The word is especially common in statistics, epidemiology, economics, and machine learning, where researchers distinguish outcome variables from the accompanying variables that help account for observed differences. Covariate ultimately comes from Latin roots meaning “together” and “vary,” accurately reflecting its role as a quantity that varies alongside another. Although its everyday use is limited, it is valuable in technical writing because it identifies a variable according to its function within an analysis rather than simply naming the kind of quantity it measures.
A secondary variable included in a statistical model to help describe, predict, or adjust for variation in another variable.
"Temperature was treated as a covariate in the analysis of plant growth."
Most common in statistics and related quantitative disciplines. A covariate is defined by its role in an analysis, so it need not be subordinate or less important in every context.
Accompanying or varying with another variable, especially as an explanatory or adjustment factor in statistical analysis.
"The researchers used covariate information to improve the precision of their estimate."
Usually encountered in technical or formal contexts and commonly used before nouns such as information, adjustment, or data.
The plural is used when referring to several secondary variables or adjustment factors.
"The model was adjusted for age, income, and other demographic covariates."
A covariate is the statistical supporting actor: it travels with the variable you are trying to explain.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does covariate come from?
The word derives from Medieval Latin covariatus, meaning “varying together,” formed from covariari “to vary together,” with Latin co- meaning “together” and variari meaning “to vary.” It entered English in the 17th century, initially in the sense of something varying or occurring together with something else. English derivatives such as covariance and covariation follow the same Latin root, while variable and variant belong to the same wider family of words associated with Latin varius, “different, varied.”
Related word forms
How covariate is actually used
The term is formal and chiefly statistical, though it is also common in machine learning and related quantitative fields. It is usually used for an explanatory or adjustment variable, not for the outcome or response variable being studied.
Easily confused with covariate
A covariate is a variable included in a statistical model for explanatory or adjustment purposes, whereas a covariant is any variable that changes systematically with another.