ScheffeTest {Analitica} | R Documentation |
Scheffé Test for Multiple Comparisons
Description
Performs Scheffé's post hoc test after fitting an ANOVA model. This test compares all possible pairs of group means, using a critical value based on the F-distribution.
Usage
ScheffeTest(modelo, alpha = 0.05)
Arguments
modelo |
An object of class |
alpha |
Significance level (default is 0.05). |
Details
The Scheffé test is a conservative method, making it harder to detect significant differences, but reducing the likelihood of Type I errors (false positives). It is especially appropriate when the comparisons were not pre-planned and the number of contrasts is large.
Assumptions: normally distributed residuals and homogeneity of variances.
Advantages: - Very robust to violations of assumptions. - Suitable for complex comparisons, not just pairwise.
Disadvantages: - Very conservative; reduced power. - Not ideal for detecting small differences.
Value
An object of class "scheffe"
and "comparaciones"
, containing:
-
Resultados
: A data frame of pairwise comparisons with difference, critical value, p-value, and significance code. -
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 test name ("Scheffe").
References
Scheffé, H. (1953). "A method for judging all contrasts in the analysis of variance." Biometrika, 40(1/2), 87–104. <https://doi.org/10.1093/biomet/40.1-2.87>
Examples
data(d_e, package = "Analitica")
mod <- aov(Sueldo_actual ~ as.factor(labor), data = d_e)
resultado <- ScheffeTest(mod)
summary(resultado)
plot(resultado)