# VUM.test: Chi-square test for the variance of a Normal variable with... In RcmdrPlugin.TeachStat: R Commander Plugin for Teaching Statistical Methods

## Description

Under the assumption that the data come from a Normal distribution, it performs the hypothesis testing and the confidence interval for the variance with unknown population mean.

## Usage

 ```1 2 3``` ```VUM.test(x, sigma = 1, sigmasq = sigma^2, alternative = c("two.sided", "less", "greater"), conf.level = 0.95, ...) ```

## Arguments

 `x` a (non-empty) numeric vector of data values. `sigma` a number indicating the true value of the population standar deviation - Null hypothesis. `sigmasq` control argument. `alternative` a character string specifying the alternative hypothesis, must be one of `"two.sided"`, `"greater"` o `"less"`. You can specify just the initial letter. `conf.level` confidence level of the interval. `...` further arguments to be passed to or from methods.

## Value

A list with class `"htest"` containing the following components:

 `statistic` the value of the test statistic `parameter` the degrees of freedom for the test statistic `p.value` the p-value for the test. `conf.int` confidence interval for variance with unknown population mean associated with the specified alternative hypothesis. `estimate` vthe estimated variance. `null.value` the specified hypothesized value of the variance. `alternative` a character string describing the alternative hypothesis. `method` a character string indicating what type of statistical test was performed. `data.name` a character string giving the name of the data.

`VKM.test` , `var.test`
 ```1 2 3 4``` ```data(cars93) # Dataset provided with the package # Variance of the maximum price (MaxPrice) assuming that the population mean # price is unknown VUM.test(cars93\$MaxPrice, alternative="two.sided", sigma=11, conf.level=0.95) ```