df.WS {BivRegBLS} | R Documentation |
Calculate the degrees of freedom from the Welch-Satterthwaite equation for a linear combination of sample variances.
df.WS(variances = NULL, k = rep(1, length(variances)), dfs = NULL)
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. |
The variances
argument is mandatory while other arguments are optional.
A numeric variable with the degrees of freedom of the linear combination of the variances.
Bernard G FRANCQ
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.
df.WS(variances=c(10,15,20),k=c(1.5,2,1.3),dfs=c(8,13,11))