Performs Bartlett's test of the null that the variances in each of the groups (samples) are the same.
bartlett_test(x, g, ...)# S3 method for default
bartlett_test(x, g, ...)
A list with class "bartlett_htest"
containing the following
components:
Bartlett's K-squared test statistic.
the degrees of freedom of the approximate chi-squared distribution of the test statistic.
the p-value of the test.
a confidence interval for the mean appropriate to the specified alternative hypothesis.
the character string "Bartlett test of homogeneity of variances".
a character string giving the names of the data.
the sample variances across groups (samples).
the number of observations per group (sample)
a numeric vector of data values, or a list of numeric data vectors representing the respective samples, or fitted linear model objects (inheriting from class "lm").
a vector or factor object giving the group for the corresponding elements of x. Ignored if x is a list.
further arguments to be passed to or from methods.
In order to allow users to enjoy the functionality of bain with the familiar
stats-function bartlett.test
, we have had to make minor changes to the
function bartlett.test.default
. All rights to, and credit for, the
function bartlett.test.default
belong to the R Core Team, as indicated in the original license below.
We make no claims to copyright and incur no liability with regard to the
changes implemented in bartlett_test
.
This the original copyright notice by the R core team: File src/library/stats/R/bartlett_test.R Part of the R package, https://www.R-project.org
Copyright (C) 1995-2015 The R Core Team
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
A copy of the GNU General Public License is available at https://www.R-project.org/Licenses/
x
must be a numeric data vector, and g
must be a vector or factor object of the same length as x
giving the group for the corresponding elements of x
.
Bartlett, M. S. (1937). Properties of sufficiency and statistical tests. Proceedings of the Royal Society of London Series A 160, 268–282. DOI: 10.1098/rspa.1937.0109.
require(graphics)
plot(count ~ spray, data = InsectSprays)
bartlett_test(InsectSprays$count, InsectSprays$spray)
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