var.test: Variance test using vectors

In fhernanb/stests: Package with useful statistical tests

Variance test using vectors

Description

This function performs the test for a single variance or two variances given the vectors. This function is a generalization of var.test function from stats package.

Usage

var.test(
  x,
  y = NULL,
  alternative = "two.sided",
  null.value = 1,
  conf.level = 0.95
)

Arguments

x	a (non-empty) numeric vector of data values.
y	an optional (non-empty) numeric vector of data values.
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.
data.name	a character string giving the name of the data.

Examples

# One sample -----

# Interval confidence
duration <- c(1470, 1510, 1690, 1740, 1900, 2000, 2030,
              2010, 2190, 2200, 2290, 2380, 2390, 2480,
              2500, 2580, 2700)
var.test(x=duration, conf.level=0.95)

# Hypothesis testing
#   H0: sigma2 = 100
#   H1: sigma2 > 100
weight <- c(775, 780, 781, 795, 803, 810, 823)
res1 <- var.test(x=weight, alternative='greater', null.value=100)
res1
# Using the plot function
plot(res1)

# Two samples -----

# Hypothesis testing
#   H0: sigma1/sigma2 = 1
#   H1: sigma1/sigma2 != 1
x1 <- rnorm(50, mean = 0, sd = 2)
x2 <- rnorm(30, mean = 1, sd = 1)
res2 <- var.test(x1, x2)
res2
plot(res2, from=0, to=10)

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