Perform Levene's test for equality of variances¶

Source: man/performLeveneTest.Rd · Help: ?performLeveneTest

Tests equality of variances across groups using residuals from a linear model.

Usage¶

performLeveneTest(model, data = NULL, group)

Arguments¶

model: an object of class lm.
data: data frame used to fit model. When NULL, the default, the model frame of model is used, so group must then be a variable of the model. The model frame holds the terms of the model rather than its variables (log(x) rather than x), so a model that transforms a variable needs data, as does a model with an offset() term.
group: name of the grouping variable.

Value¶

An object of class htest containing the F statistic, p-value and degrees of freedom.

Details¶

Absolute deviations from group means are analyzed via a one-way ANOVA. The resulting \(F\) statistic has \(k-1\) and \(N-k\) degrees of freedom under the null of equal variances.

References¶

Levene, H. (1960). Robust tests for equality of variances. In Contributions to Probability and Statistics (pp. 278–292). Stanford University Press.

Brown, M. B., & Forsythe, A. B. (1974). Robust tests for the equality of variances. Journal of the American Statistical Association, 69(346), 364–367. doi:10.1080/01621459.1974.10482955

Examples¶

 data(mtcars)
 mtcars$cyl <- factor(mtcars$cyl)
 m <- lm(mpg ~ wt, data = mtcars)
 performLeveneTest(m, mtcars, "cyl")