variance.test {LearningStats}

One Sample Variance Test of a Normal Population

Description

variance.test allows to compute hypothesis tests for the variance of a Normal population in both scenarios: known or unknown population mean.

Usage

variance.test(x = NULL, s = NULL, sc = NULL, smu = NULL, mu = NULL,
  n = NULL, sigma02, alternative = "two.sided", alpha = 0.05,
  plot = TRUE, lwd = 1)

Arguments

x

a numeric vector containing the sample.

s

a single numeric value corresponding with the sample standard deviation.

sc

a single numeric value corresponding with the cuasi-standard deviation.

smu

if known, a single numeric value corresponding with the estimation of the standard deviation for known population mean.

mu

if known, a single numeric value corresponding with the population mean. Even when the user provides smu, mu is still needed.

n

a single positive integer corresponding with the sample size; not needed if the sample is provided.

sigma02

a single number corresponding with the variance to test.

alternative

a character string specifying the alternative hypothesis, must be one of "two.sided" (default), "greater" or "less".

alpha

a single number in (0,1), significance level.

plot

a logical value indicating whether to display a graph including the test statistic value for the sample, its distribution, the rejection region and p-value.

lwd

a single number indicating the line width of the plot.

Details

The formula interface is applicable when the user provides the sample or values of the sample characteristics (cuasi-standard deviation or sample standard deviation).

Value

A list with class "lstest" and "htest" containing the following components:

statistic

the value of the test statistic.

parameter

the degrees of freedom of the statistic's distribution.

p.value

the p-value of the test.

estimate

the cuasi-variance.

null.value

the value specified by the null.

alternative

a character string describing the alternative.

method

a character string indicating the method used.

data.name

a character string giving the names of the data.

alpha

the significance level.

dist.name

a character string indicating the distribution of the test statistic.

statformula

a character string with the statistic's formula.

reject.region

a character string with the reject region.

unit

a character string with the units.

Examples

x <- rnorm(50, mean = 1, sd = 2)
# unknown population mean
variance.test(x, sigma02 = 3.5)
variance.test(sc = sd(x), n = 50, sigma02 = 3.5)
# known population mean
variance.test(x, sigma02 = 3.5, mu = 1)
smu <- Smu(x, mu = 1)
variance.test(smu = smu, n = 50, sigma02 = 3.5)