[R] effect size

[Bruno L. Giordano]

For ANOVA one option is the partial eta squared \eta^2_p:

\eta^2_p=SSeffect/(SSeffect+SSerror)

For multiple regression (continuous predictors) you might use the
standardized parameter estimate, the regression coefficient you obtain
standardizing the predictor: the larger the absolute value, the larger the
size of the effect.

You might take a look at:

S. Olejnik and J. Algina, (2003), Generalized eta and omega squared
statistics: measures of effect size for some common research designs,
Psychol Methods. 8(4):434-47.

and, if you have repeated measures:

R. Bakeman (2005), Recommended effect size statistics for repeated measures
designs, Behavior Research Methods, 37 (3), 379-384.

    Bruno


----- Original Message ----- 
From: "Matthew Bridgman" <m.bridgman at sbcglobal.net>
To: <r-help at stat.math.ethz.ch>
Sent: Wednesday, June 21, 2006 5:01 PM
Subject: [R] effect size


> Does anyone know a simple way of calculating effect sizes?
>
> Thanks
> MB
>
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