R help - Nov 2011 - path.diagram in SEM--display covariances without variances

Forgive me if I'm posting to the wrong place....It's my first time
posting.

Here's the situation: I'm using the sem package and making path
diagrams using path.diagrams. Suppose I have the following code:

#install.packages("ggm")
require(ggm)
cor = rcorr(7)
nm = c("SOF", "IWF", "PWF", "FSC",
"FSF", "EF", "GPA")


ram = specify.model()
	PWF -> FSF, a, NA
	PWF -> FSC, b, NA
	SOF -> FSF, c, NA
	SOF -> FSC, d, NA
	IWF -> FSF, e, NA
	IWF -> FSC, f, NA		
	FSC -> EF, g, NA
	FSF -> EF, h, NA
	EF -> GPA, i, NA
	PWF <-> IWF, j, NA
	PWF <-> SOF, k, NA
	SOF <-> IWF, l, NA
	PWF <-> PWF, d1, NA
	SOF <-> SOF, d2, NA
	IWF <-> IWF, d3, NA
	FSC <-> FSC, d4, NA
	FSF <-> FSF, d5, NA
	EF <-> EF, d6, NA
	GPA <-> GPA, d7, NA			
				


sem.mod = sem(ram, cor, N=1656, obs.variables=nm)

path.diagram(sem.mod, 'path/to/file/plot', ignore.double=FALSE,
edge.labels="values", standardize=TRUE, min.rank=c("IWF",
"SOF",
"PWF"))

The diagram is produces is hard to read because of the many variances
that are shown. The covariance estimates are important for my diagram,
but the variances are not. Is there a way to suppress the variance
arrows without suppressing the covariance arrows?

-- 
Dustin Fife
Graduate Student, Quantitative Psychology
University of Oklahoma

Dear Dustin,
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Dustin Fife
> Sent: November-09-11 10:57 AM
> To: r-help at r-project.org
> Subject: [R] path.diagram in SEM--display covariances without variances
> 
> Forgive me if I'm posting to the wrong place....It's my first time
> posting.
> 
> Here's the situation: I'm using the sem package and making path
> diagrams using path.diagrams. Suppose I have the following code:
> 
. . .
> The diagram is produces is hard to read because of the many variances
> that are shown. The covariance estimates are important for my diagram,
> but the variances are not. Is there a way to suppress the variance
> arrows without suppressing the covariance arrows?
No, but (1) pathDiagram() (the name of the function in the current version
of the sem package) produces an editable text file, from which you could
remove the arrows that you don't want to see; and (2) you could modify
pathDiagram() -- the code for the function is, after all, available to you
-- so that it does what you want.

I hope this helps,
 John

--------------------------------
John Fox
Senator William McMaster
  Professor of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox


> 
> --
> Dustin Fife
> Graduate Student, Quantitative Psychology University of Oklahoma
> 
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