Can Package SEM do mean structural analysis?

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?

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?

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
equation.

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?

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.