Date: Wed, 21 Sep 2005 14:42:38 0500
ReplyTo: "Swank, Paul R" <Paul.R.Swank@uth.tmc.edu>
Sender: "SPSSX(r) Discussion" <SPSSXL@LISTSERV.UGA.EDU>
From: "Swank, Paul R" <Paul.R.Swank@uth.tmc.edu>
Subject: Re: Regresssion Plot in SPSS
ContentType: text/plain; charset="iso88591"
The sum of the standardized coefficients do not necessarily add to one. If that were the case, the standardized coefficient
for a simple regression would always be one. Standardized coefficients are in standrad units so that a difference of 1 sd on the predictor predicts a beta (standardized coefficient) standard deviation change in the DV. Use of standardized coefficients to determine strength of association should be done cautiously as standardizedcoefficients are more subject to smapling fluctuations.
Paul R. Swank, Ph.D.
Professor, Developmental Pediatrics
Director of Research, Center for Improving the Readiness of Children for Learning and Education (C.I.R.C.L.E.)
Medical School
UT Health Science Center at Houston
Original Message
From: SPSSX(r) Discussion [mailto:SPSSXL@LISTSERV.UGA.EDU] On Behalf Of Vishal Dave
Sent: Wednesday, September 21, 2005 12:53 PM
To: SPSSXL@LISTSERV.UGA.EDU
Subject: Re: Regresssion Plot in SPSS
Karl,
Since your variables are not standardized, the coefficients won't add up to 1.0. You have to covert the variables in standardized variables and then run the regression model. It will give you model with intercept = 0 and sum(coefficients) = 1. This will also take care of having different nonstandardized variables with different mean and SD.
Vishal.
Original Message
From: SPSSX(r) Discussion [mailto:SPSSXL@LISTSERV.UGA.EDU] On Behalf Of Karl Koch
Sent: Wednesday, September 21, 2005 12:48 PM
To: SPSSXL@LISTSERV.UGA.EDU
Subject: Re: Regresssion Plot in SPSS
So, what you are saying is I have to create first a new regression model that only includes A and C. Then only use the unstandarized regression coefficients. Did I understand you correctly?
What is the difference to the standarized coefficients? Do the standarized coefficients somehow add up to 1.0 so that they can be seen as percentage of magnitiude?
Kind Regards,
Karl
>  Ursprüngliche Nachricht 
> Von: "Swank, Paul R" <Paul.R.Swank@uth.tmc.edu>
> An: SPSSXL@LISTSERV.UGA.EDU
> Betreff: Re: Regresssion Plot in SPSS
> Datum: Wed, 21 Sep 2005 12:35:19 0500
>
> No, you are using the unstandardized intercept but the standardized
> regression coefficients. And because B may bias the weights for A and
> C,
you need
> to run the regression again without B. The coefficients for Aand C
> will likely change. Then use the unstandardized coefficients for the
> regression equation.
>
>
> Paul R. Swank, Ph.D.
> Professor, Developmental Pediatrics
> Director of Research, Center for Improving the Readiness of Children
> for Learning and Education (C.I.R.C.L.E.) Medical School UT Health
> Science Center at Houston
>
> Original Message
> From: Karl Koch [mailto:TheRanger@gmx.net]
> Sent: Wednesday, September 21, 2005 10:36 AM
> To: Swank, Paul R; Mailinglist SPSS
> Subject: RE: Regresssion Plot in SPSS
>
> Hello Paul,
>
> Yes, I agree. Given the fact that now I only have two paramters left
> (=being significant), is this the correct equation (keeping in mind
> the
table
> below)?
>
> Y = 4.195  0.319 * A  0.442 * C + e
>
> What would be e in this case? I have standard erros for each parameter...
>
> Kind Regards,
> Karl
>
> 
> Model Unstd. Coeff. Std. Coeff. t Sig.
> B Std. Error Beta
> 
> 1(Constant) 4.195 .070 58.971 .000
> A .779 .042 .319 18.278 .000
> B .028 .046 .010 .618 .534
> C 1.635 .064 .442 25.354 .000
> 
>
>
> >
> > Drop B from the model first as it could bias the parameters for A and C.
> >
>
> 
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