```Date: Wed, 17 Dec 2008 07:43:11 -0600 Reply-To: "Peck, Jon" Sender: "SPSSX(r) Discussion" From: "Peck, Jon" Subject: Re: Gram Schmidt orthogonalization procedure Comments: To: Dulce Subida In-Reply-To: A<200812171307.mBHBl18i020280@malibu.cc.uga.edu> Content-Type: text/plain; charset="US-ASCII" -----Original Message----- From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of Dulce Subida Sent: Wednesday, December 17, 2008 6:07 AM To: SPSSX-L@LISTSERV.UGA.EDU Subject: [SPSSX-L] Gram Schmidt orthogonalization procedure Hi everyone! I need to get a Gaussian logistic model in SPSS, to predict the probability of occurence of a species (binary dependent variable) as a function of an environmental variable (x: continuous independent variable). I thought I could simply perform the binary logistic regression, using x and x2 as independent variables in the model. However in such case I think I will have a severe problem of multicollinearity (between x and x2). I thought I could orthogonalize both independent variables in order to surpass that problem. Does anyone know how can I run the Gram Schmidt orthogonalization procedure in SPSS, or does anyone know the syntaxis for it? [>>>Peck, Jon] Orthogonalizing the predictors first is not going to help. The regression calculations already partial out the variable effects. Imagine, for example, that your predictors are perfectly correlated. One would then be zero after orthogonalization, and you still would not get any better coefficient estimates. The MATRIX procedure can handle this sort of calculation, but the problem you have is not one of calculation. HTH, Jon Peck Thank you a lot for your help! ===================== 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 ===================== 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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