levene.test

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Levene's Test

Computes Levene's test for homeogeneity of variance across groups.

Keywords
htest
Usage
levene.test(y, ...)
## S3 method for class 'formula':
levene.test(y, ...)
## S3 method for class 'lm':
levene.test(y, ...)
## S3 method for class 'default':
levene.test(y, group, ...)
Arguments
y
response variable for the default method, or lm or formula object. If y is a linear-model object or a formula, the variables on the right-hand-side of the model must all be factors and must be completely cr
group
factor defining groups.
...
arguments to be passed down, e.g., data for the formula and lm methods.
Details

The version of Levene's test implemented here is based on absolute deviations from the group medians. Other, less robust, versions, not implemented, are based on absolute deviations from group means or trimmed means.

Value

  • returns an object meant to be printed showing the results of the test.

Note

adapted from a response posted by Brian Ripley to the R-help email list.

References

Fox, J. (1997) Applied Regression, Linear Models, and Related Methods. Sage.

Aliases
  • levene.test
  • levene.test.formula
  • levene.test.lm
  • levene.test.default
Examples
with(Moore, levene.test(conformity, fcategory))
## Levene's Test for Homogeneity of Variance
##       Df F value Pr(>F)
## group  2   0.046 0.9551
##       42  

with(Moore, levene.test(conformity, interaction(fcategory, partner.status)))
## Levene's Test for Homogeneity of Variance
##       Df F value Pr(>F)
## group  5  1.4694 0.2219
##       39 

levene.test(conformity ~ fcategory*partner.status, data=Moore)
levene.test(lm(conformity ~ fcategory*partner.status, data=Moore))
Documentation reproduced from package car, version 1.2-16, License: GPL (>= 2)

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