TeachingDemos (version 2.10)

sigma.test: One sample Chi-square test for a population variance

Description

Compute the test of hypothesis and compute a confidence interval on the variance of a population.

Usage

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

Arguments

x

Vector of data values.

sigma

Hypothesized standard deviation of the population.

sigmasq

Hypothesized variance of the population.

alternative

Direction of the alternative hypothesis.

conf.level

Confidence level for the interval computation.

…

Additional arguments are silently ignored.

Value

An object of class htest containing the results

Details

Many introductory statistical texts discuss inference on a single population variance and introduce the chi-square test for a population variance as another example of a hypothesis test that can be easily derived. Most statistical packages do not include the chi-square test, perhaps because it is not used in practice very often, or because the test is known to be highly sensitive to nonnormal data. For the two-sample problem, see var.test.

See Also

var.test, print.htest

Examples

# NOT RUN {
x <- rnorm(20, mean = 15, sd = 7)
sigma.test(x, sigma = 6)

# }