BivRegBLS (version 1.1.1)

df.WS: Degrees of freedom by Welch-Satterthwaite

Description

Calculate the degrees of freedom from the Welch-Satterthwaite equation for a linear combination of sample variances.

Usage

df.WS(variances = NULL, k = rep(1, length(variances)), dfs = NULL)

Arguments

variances

a numeric vector for the variances.

k

a numeric vector with the multiplicative constants.

dfs

a numeric vector with the degrees of freedom of each variance.

Value

A numeric variable with the degrees of freedom of the linear combination of the variances.

Details

The variances argument is mandatory while other arguments are optional.

References

Satterthwaite FE. An Approximate Distribution of Estimates of Variance Components. Biometrics Bulletin, 1946, 2: 110-114. Welch BK. The generalization of "student's" problem when several different population variances are involved. Biometrika, 1947, 34: 28-35.

Examples

# NOT RUN {
df.WS(variances=c(10,15,20),k=c(1.5,2,1.3),dfs=c(8,13,11))
# }