sd
Standard Deviation
This function computes the standard deviation of the values in
x.
If na.rm is TRUE then missing values are removed before
computation proceeds.
- Keywords
- univar
Usage
sd(x, na.rm = FALSE)Arguments
- x
- a numeric vector or an R object which is coercible to one
by
as.double(x). - 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.
See Also
Examples
library(stats)
sd(1:2) ^ 2
Community examples
The standard deviation of random numbers should be close to (but not exactly) what you ask for. ```{r} x <- rnorm(1000, sd = 5) sd(x) ``` If there are any missing values, the standard deviation is also missing. ```{r} sd(c(1, 2, NA)) ``` You can exclude missing values by setting `na.rm = TRUE`. ```{r} sd(c(1, 2, NA), na.rm = TRUE) ``` If `x` has length 1 or 0, the result is `NA`. ```{r} sd(1) sd(numeric()) ```