Levene's Test for Homogeneity of Variance
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)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.