Analitica (version 2.1.2)

T2Test: Tamhane's T2 Post Hoc Test

Description

Performs the Tamhane T2 test for pairwise comparisons after an ANOVA model, assuming unequal variances and/or unequal sample sizes. This test is appropriate when the assumption of homogeneity of variances is violated, such as when Levene's test or Bartlett's test is significant.

Usage

T2Test(modelo, alpha = 0.05)

Value

An object of class "tamhanet2" and "comparaciones", containing:

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

• Promedios: A named numeric vector of group means.

• Orden_Medias: A character vector with group names ordered from highest to lowest mean.

• Metodo: A character string indicating the method used ("Tamhane T2").

Arguments

modelo

An object of class aov or lm.

alpha

Significance level (default is 0.05).

Details

The test uses a modified t-test with Welch-Satterthwaite degrees of freedom and a conservative approach to control for multiple comparisons.

Advantages: - Controls Type I error under heteroscedasticity. - No assumption of equal sample sizes.

Disadvantages: - Conservative; may reduce power. - Not as powerful as Games-Howell in some contexts.

References

Tamhane, A. C. (1977). "Multiple comparisons in model I one-way ANOVA with unequal variances." Communications in Statistics - Theory and Methods, 6(1), 15–32. <https://doi.org/10.1080/03610927708827524>

Examples

data(d_e, package = "Analitica")
mod <- aov(Sueldo_actual ~ as.factor(labor), data = d_e)
resultado <- T2Test(mod)
summary(resultado)
plot(resultado)