[R] Can Package SEM do mean structural analysis?

Mitsuo Igarashi mitsu5 at ruby.famille.ne.jp
Sun May 25 07:03:42 CEST 2003

Dear John:

Thank you very much for your prompt explanation on the 
present possibilities of SEM.

I am not a statistician so that I can not figure out the raw sums-of-squares-and-products matrix.
And I will do with SEM in the area without mean structural 

I appreciate your good teaching at every time.
Mitsuo Igarashi
mitsu5 at ruby.famille.ne.jp

John Fox <jfox at mcmaster.ca> wrote:

> 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 
> program.
> 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,
>   John
> 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?

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