VarTest {DescTools}  R Documentation 
ChiSquare Test for One Variance and F Test to Compare Two Variances
Description
Performs either a one sample chisquared test to compare the variance of a vector with a given value or an F test to compare the variances of two samples from normal populations.
Usage
VarTest(x, ...)
## Default S3 method:
VarTest(x, y,
alternative = c("two.sided", "less", "greater"),
ratio = 1, sigma.squared = 1,
conf.level = 0.95, ...)
## S3 method for class 'formula'
VarTest(formula, data, subset, na.action, ...)
Arguments
x , y 
numeric vectors of data values. 
alternative 
a character string specifying the alternative
hypothesis, must be one of 
ratio 
the hypothesized ratio of the population variances of

sigma.squared 
a number indicating the true value of the variance, if one sample test is requested. 
conf.level 
confidence level for the returned confidence interval. 
formula 
a formula of the form 
data 
an optional matrix or data frame (or similar: see

subset 
an optional vector specifying a subset of observations to be used. 
na.action 
a function which indicates what should happen when
the data contain 
... 
further arguments to be passed to or from methods. 
Details
The formula interface is only applicable for the 2sample tests.
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
.
Value
A list with class "htest"
containing the following components:
statistic 
the value of the F test statistic. 
parameter 
the degrees of the freedom of the F distribution of the test statistic. 
p.value 
the pvalue of the test. 
conf.int 
a confidence interval for the ratio of the population variances. 
estimate 
the ratio of the sample variances of 
null.value 
the ratio of population variances under the null. 
alternative 
a character string describing the alternative hypothesis. 
method 
the character string

data.name 
a character string giving the names of the data. 
Author(s)
Andri Signorell <andri@signorell.net> (One sample test)
Two Sample test and help text from RCore.
See Also
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) twosample tests for difference in scale.
Examples
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.