check_homogeneity function

Check model for homogeneity of variances

Check model for homogeneity of variances between groups described by independent variables in a model.

check_homogeneity(x, method = c("bartlett", "fligner", "levene", "auto"), ...)

## S3 method for class 'afex_aov'
check_homogeneity(x, method = "levene", ...)

Arguments

• x: A linear model or an ANOVA object.
• method: Name of the method (underlying test) that should be performed to check the homogeneity of variances. May either be "levene" for Levene's Test for Homogeneity of Variance, "bartlett" for the Bartlett test (assuming normal distributed samples or groups), "fligner" for the Fligner-Killeen test (rank-based, non-parametric test), or "auto". In the latter case, Bartlett test is used if the model response is normal distributed, else Fligner-Killeen test is used.
• ...: Arguments passed down to car::leveneTest().

Returns

Invisibly returns the p-value of the test statistics. A p-value < 0.05 indicates a significant difference in the variance between the groups.

Note

There is also a c("list("plot()")", "-method")

implemented in the c("list("see")", "-package").

Examples

model <<- lm(len ~ supp + dose, data = ToothGrowth)
check_homogeneity(model)

# plot results
if (require("see")) {
  result <- check_homogeneity(model)
  plot(result)
}

See Also

Other functions to check model assumptions and and assess model quality: check_autocorrelation(), check_collinearity(), check_convergence(), check_heteroscedasticity(), check_model(), check_outliers(), check_overdispersion(), check_predictions(), check_singularity(), check_zeroinflation()