Date: Fri, 26 Sep 2008 10:22:12 +0100
Reply-To: Garry Gelade <garry@business-analytic.co.uk>
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: Garry Gelade <garry@business-analytic.co.uk>
Subject: Re: SPSS regression coefficients and effect size
In-Reply-To: <BLU137-DAV618A23DD5E3332C40441EB2470@phx.gbl>
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Marsha & Mike
It depends what her chair means (or think he means) by 'effect size'. One
thing you can easily do in SPSS is to compute the change in r-squared when
an IV is added to the regression equation - on the regression dialogue box,
put each IV in a separate block, click Statistics and tick the R-squred
change box.
However, the answers you get will depend on the order the variables are
entered into the equation. One measure of effect size therefore is to find
the change in R-squared when the predictor is added LAST. So if you had 3
predictors, X,Y and Z, the effect size for Z would be the change in R-sq
when Z is added to a regression model containing X and Y; the effect size
for X would be the change in R-sq when X is added to a regression model
containing Y and Z, and so on.
If you have mutliple dummy variables representing a single category, I would
treat the dummies as a single block.
Garry Gelade
-----Original Message-----
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
Marsha and Mike SZYMCZUK
Sent: 26 September 2008 02:37
To: SPSSX-L@LISTSERV.UGA.EDU
Subject: SPSS regression coefficients and effect size
A co-worker asked me to help her with her dissertation using SPSS
regression.
Her dissertation chair is asking her to compute effect sizes on the
significant regression coefficients. This is not a standard SPSS option.
She has both categorical and continuous variables.
Any ideas?
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