VarTest(x, ...)
"VarTest"(x, y, alternative = c("two.sided", "less", "greater"), ratio = 1, sigma.squared = 1, conf.level = 0.95, ...)
"VarTest"(formula, data, subset, na.action, ...)"two.sided" (default),
"greater" or "less". You can specify just the initial
letter.x and y.lhs ~ rhs where lhs
is a numeric variable giving the data values and rhs a factor
with two levels giving the corresponding groups.model.frame) containing the variables in the
formula formula. By default the variables are taken from
environment(formula).NAs. Defaults to
getOption("na.action")."htest" containing the following components:
x and
y."F test to compare two variances". The null hypothesis is that the ratio of the variances of the
populations from which x and y were drawn, or in the
data to which the linear models x and y were fitted, is
equal to ratio.
var.test, bartlett.test for testing homogeneity of variances in
more than two samples from normal distributions;
ansari.test and mood.test for two rank
based (nonparametric) two-sample tests for difference in scale.
x <- rnorm(50, mean = 0, sd = 2)
# One sample test
VarTest(x, sigma.squared = 2.5)
# two samples
y <- rnorm(30, mean = 1, sd = 1)
VarTest(x, y) # Do x and y have the same variance?
VarTest(lm(x ~ 1), lm(y ~ 1)) # The same.
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