Английская Википедия:Greenhouse–Geisser correction

Материал из Онлайн справочника
Перейти к навигацииПерейти к поиску

Шаблон:Short description The Greenhouse–Geisser correction <math>\widehat{\varepsilon}</math> is a statistical method of adjusting for lack of sphericity in a repeated measures ANOVA. The correction functions as both an estimate of epsilon (sphericity) and a correction for lack of sphericity. The correction was proposed by Samuel Greenhouse and Seymour Geisser in 1959.[1]

The Greenhouse–Geisser correction is an estimate of sphericity (<math>\widehat{\varepsilon}</math>). If sphericity is met, then <math> \varepsilon = 1 </math>. If sphericity is not met, then epsilon will be less than 1 (and the degrees of freedom will be overestimated and the F-value will be inflated).[2] To correct for this inflation, multiply the Greenhouse–Geisser estimate of epsilon to the degrees of freedom used to calculate the F critical value.

An alternative correction that is believed to be less conservative is the Huynh–Feldt correction (1976). As a general rule of thumb, the Greenhouse–Geisser correction is the preferred correction method when the epsilon estimate is below 0.75. Otherwise, the Huynh–Feldt correction is preferred.[3]

See also

References

Шаблон:Reflist

Шаблон:Statistics-stub