[R] Can Package SEM do mean structural analysis?

John Fox jfox at mcmaster.ca
Sat May 24 16:42:20 CEST 2003

Dear Mitsuo,

My intention in writing the sem package was to provide a basic 
structural-equation facility for R. I haven't made explicit provision for 
models with means, but it might be possible to fit such models by using the 
raw sums-of-squares-and-products matrix among the observed variables 
(perhaps divided by n) as input.  It might be necessary to make small 
modifications to degrees of freedom, etc.

I'm afraid that I don't have time now to figure out whether this will work 
and, if so, precisely how to do it, but you're welcome to try. If you get 
it to work, I'd be interested in the answer. If this approach doesn't work, 
then incorporating means would likely require major modifications to the 

There are, by the way, several other things that dedicated 
structural-equation software does that the sem package does not -- e.g., 
analysis by groups and for ordinal observed variables. I may, at some 
point, extend the package in these directions, but I don't have plans at 
the moment to do so.

Good luck,

At 10:53 PM 5/24/2003 +0900, you wrote:

>I am wondering whether Package SEM can do with intercepts and
>means in its structural analysis.
>If it can not calculate, how can I make a supplemental function
>in R?

John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox

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