LeveneTest {DescTools}  R Documentation 
Levene's Test for Homogeneity of Variance
Description
Computes Levene's test for homogeneity of variance across groups.
Usage
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, ...)
Arguments
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., 
Value
returns an object meant to be printed showing the results of the test.
Note
This function was previously published as leveneTest() in the library(car) and has been integrated here without logical changes.
Author(s)
John Fox jfox@mcmaster.ca; original generic version
contributed by Derek Ogle
adapted from a response posted by Brian Ripley to the rhelp email list.
References
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.
See Also
fligner.test
for a rankbased (nonparametric)
k
sample test for homogeneity of variances;
mood.test
for another rankbased twosample 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 pvalues for the
AnsariBradley test, as well as different methods for handling ties.
Examples
## 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)