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Single-Factor Between-Subjects Analysis of Covariance

Single-factor between-subjects analysis of covariance (ANCOVA), also known as one-way ANCOVA, is an extension of single-factor between-subjects ANOVA. If some of the variations in the dependent variable scores are caused by the effect of another continuous variable (covariate), use of ANCOVA will remove this variation from the error or random variance, resulting in increased sensitivity of the test for treatment effects.


One-Way Between-Subjects ANCOVA Output

The default output includes the one-way ANCOVA table. The additional output depends on selected options, and can include the means table, the test results for homogeneity of variance, the test results for homogeneity of regression, and table report for the chosen multiple comparison test.

The ANCOVA Table

In the analysis of covariance, the sum of the squared deviations from the mean (Sum of Squares), the degrees of freedom (df), and Mean Square computed for each of the variability components, are all adjusted values.

Testing for Homogeneity of Regression