std.dev: Calculate a Sample or Population Standard Deviation
In DrPaulWilliamson/ENVS450: Helper functions for ENVS450

Description Usage Arguments Value Note Author(s) Examples

Calculates the standard deviation of a set of numeric values, making an appropriate adjustment if using population rather than sample data.

1	std.dev(x, na.rm=TRUE, sample=TRUE)

`x`	A numeric vector.
`na.rm`	If `TRUE` (default) observations with a missing value of `x` are removed before applying the test.
`sample`	If `TRUE` (default), calculation uses n-1 in the denominator. If `FALSE`, uses n instead, as per standard statistical theory.

Numeric. Returns the value of the calculated standard deviation.

The sd function supplied as part of the base R xstats package assumes that the data are from a sample and offers no option to calculate the correct standard deviation for population data. The std.dev function offers this additional facility.

Paul Williamson

## Calculate standard deviation of a sample (default)
std.dev(survey$Height)

## For a sample, std.dev returns same result as stats:::sd function
std.dev(survey$Height) == sd(survey$Height)

## Calculation standard deviation of a population
std.dev(survey$Height, sample = FALSE)