satterthwaite: Satterthwaite Approximation

In PhilipPallmann/SimLongi: Simultaneous Inference in Longitudinal Data Settings

Description

Computes Satterthwaite's approximation to the degrees of freedom.

Usage

satterthwaite(var, n, df=n-1)

Arguments

var	A vector of numeric values giving the independent sample variances.
n	A vector of integers giving the sample sizes.
df	A vector of numeric values giving the degrees of freedom for the independent sample variances. Default is n-1.

Value

A numeric value giving the pooled degrees of freedom according to the Satterthwaite approximation.

Author(s)

Philip Pallmann [e-mail]

References

Satterthwaite, F. E. (1941) Synthesis of variance. Psychometrika, 6(5), 309–316.

Satterthwaite, F. E. (1946) An approximate distribution of estimates of variance components. Biometrics Bulletin, 2(6), 110–114.

Examples

# Perfectly homoscedastic
satterthwaite(rep(2, 3), rep(10, 3))

# Mildly heteroscedastic
satterthwaite(c(1.9, 2, 2.1), rep(10, 3))

# Strongly heteroscedastic
satterthwaite(1:3, rep(10, 3))

PhilipPallmann/SimLongi documentation built on May 8, 2019, 1:34 a.m.