Re: standardized values in multilevel

Posted by Ryan on Jan 05, 2012; 1:12am
URL: http://spssx-discussion.165.s1.nabble.com/standardized-values-in-multilevel-tp5117328p5121481.html

Gene,

One of the examples provided in the previously referenced book (page 22) applied the standardization formula to a fixed effect associated with a 2nd level predictor. 

For the record, I am generally not in favor of standardizing regression coefficients in order to assess relative importance for reasons you've probably heard a number of times.

Ryan

On Wed, Jan 4, 2012 at 9:51 AM, Gene Maguin <[hidden email]> wrote:

Thanks, for all the replies to my request (and the citation). I’ll do the standardized analysis if I need to but what I was hoping for was what Ryan posted. However, here is the point I’m not sure about. In the model were x is the level 2 predictor of variation of the y intercept

 

Mixed y with x/fixed x/. . . .

 

I can get sd of x from the univariate stats. However, for sd of y do I want the univariate stats value of y, as would be true in an ordinary one level regression, or do I need the sd of the level 1 intercept? And, if I need the sd of the level 1 intercept, how can I get that from mixed?

 

Thanks, Gene Maguin

 

From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of R B
Sent: Tuesday, January 03, 2012 8:12 PM
To: [hidden email]
Subject: Re: standardized values in multilevel

 

Gene,

 

A simple approach would be to fit the linear mixed model using the original variables and then to apply the following formula:

 

std coeff = [(unstd coeff) * (sd of x)] / (sd of y)

 

You could enter "standardized" variables into the linear mixed model, but keep in mind that the variance components will likely change. 

The formula above, along with a detailed discussion, can be found in "Multilevel Analysis: techniques and applications" by J.J. Hox.

 

HTH,

 

Ryan

On Tue, Jan 3, 2012 at 11:27 AM, Gene Maguin <[hidden email]> wrote:

I know this is a controversial request because I have seen Cam's (and
other's) citations on both Multilevel and Semnet on this topic and I don't
want to have that discussion. I'd like a response to the technical question
of whether (and how) standardized values of fixed effects can be computed
given spss (I may have missed it but I don't think mixed can output those
values). If there is a computational citation, that would be fine.
Concretely, given
Mixed f with b c/fixed b c/print solution/random intercept | subject(xx)
covtype(id).
I get unstandardized regression coefficients for b and c. How do I
standardize them? I know this is possible in mplus. I'd like to do it in
spss.

Thanks, Gene Maguin

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