From: John Fox <jfox_at_mcmaster.ca>

Date: Thu 17 Aug 2006 - 22:57:32 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu Aug 17 23:11:59 2006

Date: Thu 17 Aug 2006 - 22:57:32 EST

Dear Rick,

> -----Original Message-----

*> From: r-help-bounces@stat.math.ethz.ch
**> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Rick Bilonick
**> Sent: Thursday, August 17, 2006 7:07 AM
**> To: John Fox
**> Cc: 'R Help'; 'Rick Bilonick'
**> Subject: Re: [R] Specifying Path Model in SEM for CFA
**>
*

. . .

*>
**> I'm trying to build a multivariate receptor model as
**> described by Christensen and Sain (Technometrics, vol 44 (4)
**> pp. 328-337). The model is
**>
**> x_t = Af_t + e_t
**>
**> where A is the matrix of nonnegative source compositions, x_t
**> are the observed pollutant concentrations at time t, and f_t
**> are the unobserved factors. The columns of A are supposed to
**> sum to no more than 100%. They say they are using a latent
**> variable model. If sem can't handle this, do you know of
*

> another R package that could?

*>
*

sem() handles only equality constraints among parameters, and this model requires linear inequality constraints.

I'm sorry that I can't be of more direct help. John

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu Aug 17 23:11:59 2006

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