vartest (version 1.3)

g.test: G Test

Description

g.test performs G variance homogeneity test.

Usage

g.test(formula, data, alpha = 0.05, na.rm = TRUE, verbose = TRUE)

Value

A list with class "vht" containing the following components:

statistic

the corresponding test statistic.

parameter

the parameter(s) of the approximate F distribution of the test statistic.

p.value

the p-value of the test.

method

the character string "G Test".

data

a data frame containing the variables in which NA values (if exist) are removed.

formula

a formula of the form lhs ~ rhs where lhs gives the sample values and rhs the corresponding groups.

Arguments

formula

a formula of the form lhs ~ rhs where lhs gives the sample values and rhs the corresponding groups.

data

a tibble or data frame containing the variables in formula.

alpha

the level of significance to assess variance homogeneity. Default is set to alpha = 0.05.

na.rm

a logical value indicating whether NA values should be stripped before the computation proceeds.

verbose

a logical for printing output to R console.

Author

Gozde Cosar and Osman Dag

References

UE't Lam, R. (2010). Scrutiny of Variance Results for Outliers: Cochran's Test Optimized. Analytica Chimica Acta, 659(1-2), 68-84.

Wang, Y., Gil, P.R., Chen, Y.H., Kromrey, J.D., Kim, E.S., Pham, T., Nguyen, D., Romano, J.L. (2017). Comparing the Performance of Approaches for Testing the Homogeneity of Variance Assumption in One-Factor Anova Models. Educational and Psychological Measurement, 77:2, 305-329.

Examples

library(vartest)

g.test(Sepal.Length ~ Species, data = iris)

out <- g.test(Sepal.Length ~ Species, data = iris, verbose = FALSE)
summary(out)