```Date: Fri, 26 Sep 2008 10:22:12 +0100 Reply-To: Garry Gelade Sender: "SPSSX(r) Discussion" From: Garry Gelade Subject: Re: SPSS regression coefficients and effect size Comments: To: Marsha and Mike SZYMCZUK In-Reply-To: Content-Type: text/plain; charset="us-ascii" 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? ======= To manage your subscription to SPSSX-L, send a message to LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD __________ NOD32 3472 (20080925) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com ===================== To manage your subscription to SPSSX-L, send a message to LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD ```

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