SNKTest {Analitica} | R Documentation |
Student-Newman-Keuls (SNK) Test for Multiple Comparisons
Description
Performs the Student-Newman-Keuls (SNK) post hoc test for pairwise comparisons after fitting an ANOVA model. The test uses a stepwise approach where the critical value depends on the number of means spanned between groups (range r).
Usage
SNKTest(modelo, alpha = 0.05)
Arguments
modelo |
An object of class |
alpha |
Significance level (default is 0.05). |
Details
SNK is more powerful but less conservative than Tukey’s HSD, increasing the chance of detecting real differences while slightly raising the Type I error rate.
Assumptions: normality, homogeneity of variances, and independence of observations.
Advantages: - More powerful than Tukey when differences are large. - Intermediate control of Type I error.
Disadvantages: - Error control is not family-wise. - Type I error increases with more comparisons.
Value
An object of class "snk"
and "comparaciones"
, containing:
-
Resultados
: A data frame with pairwise comparisons, including mean differences, critical values, 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 test used ("SNK").
References
Student, Newman, and Keuls (1952). "Student-Newman-Keuls Procedure". See also: <https://doi.org/10.1002/bimj.200310019>
Examples
data(d_e, package = "Analitica")
mod <- aov(Sueldo_actual ~ as.factor(labor), data = d_e)
resultado <- SNKTest(mod)
summary(resultado)
plot(resultado)