Structural Equation Models(SEM)
The model you have specified there is not an ordinary factor analysis model. This may be closer to what you are thinking of: model.RLIM <- specify.model() f1 -> R, laddR, NA f1 -> L, laddL, NA f1 -> I, laddI, NA f1 -> M, laddM, NA R <-> R, dR, NA L <-> L, dL, NA I <-> I, dI, NA M <-> M, dM, NA f1 <-> f1, NA, 1 sem.RLIM=sem(model.RLIM,tcv,101) summary(sem.RLIM) Note that the paths go from the latent factor to the manifest variables, not vice-versa. Best, -- Wolfgang Viechtbauer http://www.wvbauer.com/ Department of Methodology and Statistics Tel: +31 (0)43 388-2277 School for Public Health and Primary Care Office Location: Maastricht University, P.O. Box 616 Room B2.01 (second floor) 6200 MD Maastricht, The Netherlands Debyeplein 1 (Randwyck)
From: r-help-bounces at r-project.org [r-help-bounces at r-project.org] On Behalf Of Ralf Finne [Ralf.Finne at novia.fi]
Sent: Wednesday, November 25, 2009 5:23 PM
To: r-help at r-project.org
Subject: [R] Structural Equation Models(SEM)
Sent: Wednesday, November 25, 2009 5:23 PM
To: r-help at r-project.org
Subject: [R] Structural Equation Models(SEM)
Hi R-colleagues.
In the sem-package
i have a problem to introduce hidden variables.
As a simple example I take an ordinary factor analysis.
The program:
cmat=c(0.14855886, 0.05774635, 0.08003300, 0.04900990,
0.05774635, 0.18042029, 0.11213013, 0.03752475,
0.08003300, 0.11213013, 0.24646337, 0.03609901,
0.04900990, 0.03752475, 0.03609901, 0.31702970)
rn=c("R","L","I","M")
cn=c("R","L","I","M")
tcv=matrix(cmat,nrow=4,ncol=4,dimnames=list(rn,cn))
model.RLIM <- specify.model()
R -> f1, laddR, NA
L -> f1, laddL, NA
I -> f1, laddI, NA
M -> f1, laddM, NA
R <-> R, dR,NA
L <-> L, dL,NA
I <-> I, dI,NA
M <-> M, dM,NA
f1 <-> f1, df1,NA
sem.RLIM=sem(model.RLIM,tcv,101)
The output:
Error in dimnames(x) <- dn :
length of 'dimnames' [2] not equal to array extent
In addition: Warning messages:
1: In sem.default(ram = ram, S = S, N = N, param.names = pars, var.names = vars, :
singular Hessian: model is probably underidentified.
2: In sem.default(ram = ram, S = S, N = N, param.names = pars, var.names = vars, :
refitting without aliased parameters.
I use R version 2.10.0 (2009-10-26) under Windows XP
sem_0.9-19 version.
Where did I make a mistake? Have anyone of you knowledge
of any other package doing similar things like Confirmative Factor Analysis
Ralf Finne
Novia University of Applied Science
Vasa Finland
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