Date: Fri, 12 Aug 2005 13:07:11 -0500
Reply-To: "Swank, Paul R" <Paul.R.Swank@uth.tmc.edu>
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: "Swank, Paul R" <Paul.R.Swank@uth.tmc.edu>
Subject: Re: effect size form F and df
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d = the difference in means divided by the standard deviation. Assuming
a two group design, F is the difference between means squared over the
pooled variance multiplied by [1/n(1) + 1/n(2)] so that
effect size squared is F times [1/n(1) + 1/n(2)]. If the n's are equal
then this becomes F*(2/n) so that the effect size is the square root of
Paul R. Swank, Ph.D.
Professor, Developmental Pediatrics
UT Health Science Center at Houston
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
Sent: Friday, August 12, 2005 9:51 AM
Subject: effect size form F and df
I want to calculate cohen's d from and F and df. Does anyone know how
to do this, or if it is possible?
I was thinking that I could just use this equation, since F is just t
squared. I could take the square root of the F and then run this
syntax. Does that make sense?
COMPUTE est_dbyt = (2 * t_value) / sqrt(df) .
Matthew Pirritano, Ph.D.
National Science Foundation Post-Doctoral Fellow College of Education
Department of Individual, Family & Community Education
1 University of New Mexico
Albuquerque, NM 87131-0001