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  • Current: Jan 21, 2023

ANOVA, analysis of variance

ANOVA (analysis of variance) is a statistical test to identify significant differences (see P value) between categorical groups using a variance.

ANOVA is generally used for data containing more than three categorical groups. Depending on the number of factors, one-way ANOVA and two-way ANOVA are commonly used.

One-way ANOVA

Schematic diagram of one-way ANOVA

Two-way ANOVA

Schematic diagram of two-way ANOVA

Some important features related to ANOVA includes:

  • ANOVA is a parametric method that assumes a normal distribution.
  • ANOVA determines whether there is a significant difference between groups, but does not show that which groups are significantly different. A post-hoc test should be applied to detect the inter-group differences.

Definitions in the literature

  • An ANOVA test is a statistical test used to determine if there is a statistically significant difference between two or more categorical groups by testing for differences of means using a variance [1].