Performs Hartley's maximum F-ratio test of the null that variances in each of the groups (samples) are the same.
hartleyTest(x, ...)# S3 method for default
hartleyTest(x, g, ...)
# S3 method for formula
hartleyTest(formula, data, subset, na.action, ...)
a numeric vector of data values, or a list of numeric data vectors.
further arguments to be passed to or from methods.
a vector or factor object giving the group for the
corresponding elements of "x"
.
Ignored with a warning if "x"
is a list.
a formula of the form response ~ group
where
response
gives the data values and group
a vector or
factor of the corresponding groups.
an optional matrix or data frame (or similar: see
model.frame
) containing the variables in the
formula formula
. By default the variables are taken from
environment(formula)
.
an optional vector specifying a subset of observations to be used.
a function which indicates what should happen when
the data contain NA
s. Defaults to getOption("na.action")
.
A list with class "htest"
containing the following components:
a character string indicating what type of test was performed.
a character string giving the name(s) of the data.
the estimated quantile of the test statistic.
the p-value for the test.
the parameters of the test statistic, if any.
a character string describing the alternative hypothesis.
the estimates, if any.
the estimate under the null hypothesis, if any.
If x
is a list, its elements are taken as the samples
to be compared for homogeneity of variances. In this
case, the elements must all be numeric data vectors,
g
is ignored, and one can simply use
hartleyTest(x)
to perform the test. If the samples are not
yet contained in a list, use hartleyTest(list(x, ...))
.
Otherwise, x
must be a numeric data vector, and g
must
be a vector or factor object of the same length as x
giving the
group for the corresponding elements of x
.
Hartley's parametric test requires normality and
a nearly balanced design. The p-value of the test
is calculated with the function pmaxFratio
of the package SuppDists.
Hartley, H.O. (1950) The maximum F-ratio as a short cut test for heterogeneity of variance, Biometrika 37, 308--312.
# NOT RUN {
hartleyTest(count ~ spray, data = InsectSprays)
# }
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