HyunhFeldtEpsilon {superb}

Hyunh and Feldt's epsilon measure of sphericity

Description

HyunhFeldtEpsilon() is a measure of sphericity created by Geisser and Greenhouse (1958). The original measure was biased and therefore, Huynh and Feldt (1976) produced a revised version (note that the 1976 paper contained typos that were uncorrected in SPSS; Lecoutre (1991))

Usage

HyunhFeldtEpsilon(dta, cols)

Arguments

dta

a data.frame

cols

a vector of column names indicating the relevant columns on which to compute epsilon. Any other columns are ignored.

Value

returns the Hyunh-Feldt estimate of sphericity epsilon

References

Geisser S, Greenhouse SW (1958). “An extension of Box's results on the use of the F distribution in multivariate analysis.” Annals of Mathematical Statistics, 29(3), 885–891.

Huynh H, Feldt LS (1976). “Estimation of the Box correction for degrees of freedom from sample data in randomized block and split-plot designs.” Journal of educational statistics, 1(1), 69–82.

Lecoutre B (1991). “A correction for the \varepsilon approximate test in repeated measures designs with two or more independent groups.” Journal of Educational Statistics, 16(4), 371–372.