LeveneTest | R Documentation |
Computes Levene's test for homogeneity of variance across groups.
LeveneTest(y, ...)
## S3 method for class 'formula'
LeveneTest(formula, data, ...)
## S3 method for class 'lm'
LeveneTest(y, ...)
## Default S3 method:
LeveneTest(y, group, center=median, ...)
y |
response variable for the default method, or a |
group |
factor defining groups. |
center |
The name of a function to compute the center of each group;
|
formula |
a formula of the form |
data |
an optional matrix or data frame (or similar: see
|
... |
arguments to be passed down, e.g., |
returns an object meant to be printed showing the results of the test.
This function was previously published as leveneTest() in the library(car) and has been integrated here without logical changes.
John Fox jfox@mcmaster.ca; original generic version
contributed by Derek Ogle
adapted from a response posted by Brian Ripley to the r-help email list.
Fox, J. (2008) Applied Regression Analysis and Generalized Linear Models, Second Edition. Sage.
Fox, J. and Weisberg, S. (2011) An R Companion to Applied Regression, Second Edition, Sage.
fligner.test
for a rank-based (nonparametric)
k
-sample test for homogeneity of variances;
mood.test
for another rank-based two-sample test for a
difference in scale parameters;
var.test
and bartlett.test
for parametric
tests for the homogeneity in variance.
ansari_test
in package coin
for exact and approximate conditional p-values for the
Ansari-Bradley test, as well as different methods for handling ties.
## example from ansari.test:
## Hollander & Wolfe (1973, p. 86f):
## Serum iron determination using Hyland control sera
ramsay <- c(111, 107, 100, 99, 102, 106, 109, 108, 104, 99,
101, 96, 97, 102, 107, 113, 116, 113, 110, 98)
jung.parekh <- c(107, 108, 106, 98, 105, 103, 110, 105, 104,
100, 96, 108, 103, 104, 114, 114, 113, 108, 106, 99)
LeveneTest( c(ramsay, jung.parekh),
factor(c(rep("ramsay",length(ramsay)), rep("jung.parekh",length(jung.parekh)))))
LeveneTest( c(rnorm(10), rnorm(10, 0, 2)), factor(rep(c("A","B"),each=10)) )
## Not run:
# original example from package car
with(Moore, LeveneTest(conformity, fcategory))
with(Moore, LeveneTest(conformity, interaction(fcategory, partner.status)))
LeveneTest(conformity ~ fcategory * partner.status, data = Moore)
LeveneTest(conformity ~ fcategory * partner.status, data = Moore, center = mean)
LeveneTest(conformity ~ fcategory * partner.status, data = Moore, center = mean, trim = 0.1)
LeveneTest(lm(conformity ~ fcategory*partner.status, data = Moore))
## End(Not run)
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.