MBESS (version 4.9.3)

s.u: Unbiased estimate of the population standard deviation

Description

Transforms the usual (and biased) estimate of the standard deviation into an unbiased estimator.

Usage

s.u(s=NULL, N=NULL, X=NULL)

Value

The unbiased estimate for the standard deviation.

Arguments

s

the usual estimate of the standard deviation (i.e., the square root of the unibased estimate of the variance)

N

sample size s is based

X

vector of scores in which the unbiased estimate of the standard deviation should be calculated

Author

Ken Kelley (University of Notre Dame; )

Details

Returns the unbiased estimate for the standard deviation.

References

Holtzman, W. H. (1950). The unbiased estimate of the population variance and standard deviation. American Journal of Psychology, 63, 615--617.

Examples

set.seed(113)
X <- rnorm(10, 100, 15)

# Square root of the unbiased estimate of the variance (not unbiased)
var(X)^.5

# One way to implement the function.
s.u(s=var(X)^.5, N=length(X))

# Another way to implement the function.
s.u(X=X)