levene.test {car} | R Documentation |
Computes Levene's test for homeogeneity of variance across groups.
levene.test(y, ...) ## S3 method for class 'formula': levene.test(y, ...) ## S3 method for class 'lm': levene.test(y, ...) ## Default S3 method: levene.test(y, group, ...)
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 crossed. |
group |
factor defining groups. |
... |
arguments to be passed down, e.g., data for the
formula and lm methods. |
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.
returns an object meant to be printed showing the results of the test.
adapted from a response posted by Brian Ripley to the R-help email list.
John Fox jfox@mcmaster.ca; generic version contributed by Derek Ogle
Fox, J. (1997) Applied Regression, Linear Models, and Related Methods. Sage.
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))