```Date: Thu, 30 Apr 1998 09:32:19 -0500 Reply-To: "Nichols, David" Sender: "SPSSX(r) Discussion" From: "Nichols, David" Subject: Re: monte carlo simulations & continuous variable interactions Comments: To: Joshua Sacco An interesting question. What comes to mind would be to break the problem into pieces. That is, I don't think the method that allows you to create variables with given covariance/correlation structures is going to be able to accommodate the other issues unless you can translate them into that framework. Thus, you need to be able to specify the correlational structure desired. You could approach this from the perspective of partial correlations and work backwards to solve for the necessary bivariate correlations (the solutions would probably not be unique, so you'd have to make choices among alternative sets of values). I'm not positive that you'd be able to accommodate the desire to have x3 be a product of x1 and x2 without further trickery though. Perhaps this is a start. David Nichols Principal Support Statistician and Manager of Statistical Support SPSS Inc. nichols@spss.com ---------- From: Joshua Sacco [SMTP:josh@PILOT.MSU.EDU] Sent: Monday, April 27, 1998 11:30 PM To: SPSSX-L@UGA.CC.UGA.EDU Subject: monte carlo simulations & continuous variable interactions hi, i'm wondering if anyone has come across any SPSS matrix code (or has any ideas how on a good approach for this) to generate correlation/covariance matrices consisting of 4 continuous variables x1, x2, x3 & y where x3 is the product of x1 & x2 and x3 predicts y after controlling for x1 & x2. that is, i want to generate correlation matrices representing a situation in which two continuous variables interact to predict a third continuous variable. I've seen the code to generate simulations using regular (i.e., those with non-interacting variables) correlation matrices, and Aguinis (1997) references some code to do this for the subgroup (i.e., dichotomous moderator) case, but I don't have any good ideas about how to do this for continuous variables. I'd also like to be able to manipulate the extent of the moderation effect if possible. tia, Josh ```

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