var_test: Variance test using values
In fhernanb/stests: Package with useful statistical tests

var_test

R Documentation

Variance test using values

Description

This function performs the test for a single variance or two variances using values, not the vectors.

Usage

var_test(
  varx,
  nx,
  vary = NULL,
  ny = NULL,
  alternative = "two.sided",
  null.value = 1,
  conf.level = 0.95
)

Arguments

`varx`	sample variance for sample x.
`nx`	sample size for sample x.
`vary`	sample variance for sample y.
`ny`	sample size for sample y.
`alternative`	a character string specifying the alternative hypothesis, must be one of `two.sided` (default), `greater` or `less`. You can specify just the initial letter.
`null.value`	the hypothesized number (variance or ratio of the variances) in the null hypothesis.
`conf.level`	confidence level of the interval, by default its value is 0.95.

Value

A list with class htest containing the following components:

`statistic`	the value of the statistic.
`p.value`	the p-value for the test.
`conf.int`	a confidence interval for the variance.
`estimate`	the sample variance (or ratio of the sample variances)
`null.value`	the specified hypothesized value for alternative hypothesis.
`alternative`	a character string describing the alternative hypothesis.
`method`	a character string indicating the type of test performed.

Examples

# Examples with ONE sample

# Example 7.7.1 from Wayne (2013), http://tinyurl.com/y6z49hrw
var_test(varx=670.81, nx=16, null.value=600, alternative='two.sided')

# Exercise 7.7.5 from Wayne (2013), http://tinyurl.com/y6z49hrw
var_test(varx=30, nx=25, null.value=25, alternative='greater')

# Using the plot to illustrate Hypothesis Test
mytest1 <- var_test(varx=30, nx=25, null.value=25, alternative='greater')
mytest1
plot(mytest1)

# Examples with TWO samples

# Example 7.8 from Montgomery (1996)
var_test(varx=5.1^2, nx=12, vary=4.7^2, ny=15, conf.level=0.90)

# Example 8.17 from Montgomery (1996)
mytest2 <- var_test(varx=3.84, nx=20, vary=4.54, ny=20)
mytest2
plot(mytest2)

fhernanb/stests documentation built on March 29, 2025, 10:36 a.m.