Analitica (version 2.1.2)

GHTest: Games-Howell Post Hoc Test

Description

Performs the Games-Howell test for pairwise comparisons after ANOVA, without assuming equal variances or sample sizes. It is suitable when Levene or Bartlett test indicates heterogeneity of variances.

Usage

GHTest(modelo, alpha = 0.05)

Value

An object of class "gameshowell" and "comparaciones", which contains:

• Resultados: A data frame with pairwise comparisons, including mean differences, t-values, degrees of freedom, p-values, and significance labels.

• Promedios: A named numeric vector of group means.

• Orden_Medias: A character vector with group names ordered by their means.

• Metodo: A character string indicating the method used ("Games-Howell").

Arguments

modelo

An object from aov or lm.

alpha

Significance level (default is 0.05).

Details

Advantages: - Excellent for heteroscedastic data. - Controls Type I error across unequal group sizes.

Disadvantages: - Slightly conservative in small samples. - More complex to compute than Tukey.

References

Games, P. A., & Howell, J. F. (1976). "Pairwise Multiple Comparison Procedures with Unequal N's and/or Variances: A Monte Carlo Study". Journal of Educational Statistics, 1(2), 113–125. <https://doi.org/10.1002/j.2162-6057.1976.tb00211.x>

Examples

data(d_e, package = "Analitica")
mod <- aov(Sueldo_actual ~ as.factor(labor), data = d_e)
resultado <- GHTest(mod)
summary(resultado)
plot(resultado)