ANCOVA Calculator

Overview

The ANCOVA (Analysis of Covariance) Calculator demonstrates how to compare group means while controlling for a continuous covariate. This powerful technique combines ANOVA and regression, allowing you to test group differences after adjusting for confounding variables. Watch as ANCOVA reveals true group effects by removing variance attributable to the covariate, increasing statistical power and providing fairer comparisons.

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Tips

  • ANCOVA combines ANOVA and regression to control for continuous covariates (like age, baseline scores)
  • The covariate should be linearly related to the dependent variable but independent of the treatment
  • Adjusted means remove the effect of the covariate, showing what group means would be at the same covariate value
  • Check the homogeneity of regression slopes assumption - groups should have parallel regression lines
  • ANCOVA increases statistical power by reducing error variance
  • Compare unadjusted vs adjusted means to see the covariate’s impact
  • The F-statistic tests if adjusted group means differ significantly
  • Use when you have a confounding variable that’s continuous (for categorical confounders, use factorial ANOVA)
  • Common applications: baseline-adjusted treatment effects, controlling for age in developmental studies