sd {stats}R Documentation

Standard Deviation

Description

This function computes the standard deviation of the values in x. If na.rm is TRUE then missing values are removed before computation proceeds.

Usage

sd(x, na.rm = FALSE)

Arguments

x

a numeric vector or an R object which is coercible to one by as.vector(x, "numeric").

na.rm

logical. Should missing values be removed?

Details

Like var this uses denominator n - 1.

The standard deviation of a zero-length vector (after removal of NAs if na.rm = TRUE) is not defined and gives an error. The standard deviation of a length-one vector is NA.

Prior to R 2.14.0, sd(dfrm) worked directly for a data.frame dfrm. This is now defunct and you are expected to use sapply(dfrm, sd).

See Also

var for its square, and mad, the most robust alternative.

Examples

sd(1:2) ^ 2

[Package stats version 2.15.3 Index]