sigmaTestMenu: Variance test

In Rcmdr: R Commander

Variance test

Description

Within the "Statistics" -> "Variances" menu, a entry is provided for calculate confidence intervals and make contrasts on variance in a normal population. This option uses the function sigma.test of the package TeachingDemos. For more information see sigma.test.

Usage

sigmaTestMenu()

Details

Here is an example of "Single-Sample Variance Test..." menu entry.

Load data "BJsales" selecting from Rcmdr menu: "Data" -> "Data in packages" -> "Read data set from an attached package..." then double-click on "datasets", click on "BJsales" and on "OK".

Rcmdr reply with the following command in source pane (R Script)

data(BJsales, package="datasets")

BJsales <- as.data.frame(BJsales)

To build a confidence interval for sigma on variable x, select from Rcmdr menu: "Statistics" -> "Variances" -> "Single-sample Variance Test..." select "x". Enter 500 in the "Null hypothesis sigma0^2" field to test the hypothesis that the population variance is 500, and click OK. Rcmdr reply with the following command in source pane (R Script)

with(na.omit(BJsales), sigma.test(x, alternative='two.sided', sigmasq=500, conf.level=0.95))

And the result shown in the Output panel is

	One sample Chi-squared test for variance

data:  x
X-squared = 137.49, df = 149, p-value = 0.5184
alternative hypothesis: true variance is not equal to 500
95 percent confidence interval:
372.2253 587.0738
sample estimates:
var of x
461.3769 

Author(s)

Manuel Munoz-Marquez <[e-mail]>

Rcmdr documentation built on Sept. 25, 2026, 9:06 a.m.