VarCI {DescTools}R Documentation

Confidence Interval for the Variance

Description

Calculates the confidence interval for the variance either the classical way or with the bootstrap approach.

Usage

VarCI(x, method = c("classic", "norm", "basic", "stud", "perc", "bca"),
      conf.level = 0.95, sides = c("two.sided", "left", "right"),
      na.rm = FALSE, R = 999)

Arguments

x

a (non-empty) numeric vector of data values.

method

vector of character strings representing the type of intervals required. The value should be any subset of the values "classic", "norm", "basic", "stud", "perc", "bca". See boot.ci.

conf.level

confidence level of the interval.

sides

a character string specifying the side of the confidence interval, must be one of "two.sided" (default), "left" or "right". You can specify just the initial letter. "left" would be analogue to a hypothesis of "greater" in a t.test.

na.rm

logical. Should missing values be removed? Defaults to FALSE.

R

number of bootstrap replicates. Usually this will be a single positive integer. For importance resampling, some resamples may use one set of weights and others use a different set of weights. In this case R would be a vector of integers where each component gives the number of resamples from each of the rows of weights. See boot.

Value

a numeric vector with 3 elements:

var

variance

lwr.ci

lower bound of the confidence interval

upr.ci

upper bound of the confidence interval

Author(s)

Andri Signorell <andri@signorell.net>

See Also

MeanCI, MedianCI

Examples

VarCI(d.pizza$price, na.rm=TRUE)
VarCI(d.pizza$price, conf.level=0.99, na.rm=TRUE)

x <- c(14.816, 14.863, 14.814, 14.998, 14.965, 14.824, 14.884, 14.838, 14.916,
       15.021, 14.874, 14.856, 14.860, 14.772, 14.980, 14.919)
VarCI(x, conf.level=0.9)

# and for the standard deviation
sqrt(VarCI(x, conf.level=0.9))

# some bootstrap intervals
VarCI(x, method="norm")
VarCI(x, method="perc")
VarCI(x, method="bca")
[Package DescTools version 0.99.24 Index]