[R] Another SEM question

Tue Jul 21 09:05:46 CEST 2009

 Hello,

Perhaps this is a good point. I use the Eclipse platform. The problem was that when I first used the structure 
Z -> M, z1, NA the compiler took only the value Z ->M. Thus I erased it totally.
Maybe it is really an Eclipse problem.

Do you know how to solve this difficulty?

Thanks for all your support,
Luba

-----Urspr?ngliche Nachricht-----
Von: Jarrett Byrnes [mailto:byrnes at msi.ucsb.edu] 
Gesendet: Dienstag, 21. Juli 2009 09:01
An: Stein, Luba (AIM SE)
Cc: r-help at r-project.org
Betreff: Re: AW: [R] Another SEM question

Ah, the larger problem is in how you specify your model.  You provide  
no parameter names, nor starting estimates (even an NA).  See the sem  
help file for an example.  Basically, it must look something like as  
follows

model <- specify.model()
Z -> M, zm, NA
Z -> I, zi, NA

etc.

On Jul 20, 2009, at 11:37 PM, Stein, Luba (AIM SE) wrote:

>
> Hi,
>
>
>              [,1]          [,2]          [,3]
> [1,]  4.820719e-03 -5.558801e-05 -5.718939e-05
> [2,] -5.558801e-05  4.763194e-06 -7.661872e-06
> [3,] -5.718939e-05 -7.661872e-06  1.662150e-03
>
> This is mod.cov. It is the covariance matrix of (R, I, M).
> R, I and M are vectors of length 109 which are contained in the file  
> data4.csv.
>
> As far as I understood the package sem. I consider R, I and M as the  
> external veriables and Z as the latent variable which I will receive  
> as an result after calculating the estimated errors and parameters.  
> This is what atually is missing in the output.
> Moreover, the output provides the information about the quality of  
> the fitted model. I have to admit that this model does not fit quite  
> well.
> Nevertheless, it should provide the estimated errors like it does  
> just for the first variable Z ->M.
>
> Thanks a lot for your help,
> Luba
>
>
> -----Urspr?ngliche Nachricht-----
> Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r- 
> project.org] Im Auftrag von Jarrett Byrnes
> Gesendet: Dienstag, 21. Juli 2009 08:19
> An: Stein, Luba (AIM SE)
> Cc: r-help at r-project.org
> Betreff: Re: [R] Another SEM question
>
> You don't appear to be defining Z here.
>
> Might that be the problem?
>
> Or, I, M, and R may not be defined either.  It is unclear.  What does
> mod.cov look like?
>
> On Jul 20, 2009, at 11:11 PM, Stein, Luba (AIM SE) wrote:
>
>> Thank you for your advice. So I am sending the whole code
>>
>> data.dir <- file.path(home.dir, "Data")
>> file     <- file.path(data.dir, "data4.csv")
>>
>> SEM <- read.csv(file)
>> print(SEM)
>>
>> library(sem)
>> SEM1 <- as.matrix(cbind(SEM$R1, SEM$I1, SEM$M1))
>> print(SEM1)
>> mod.cov <- cov(SEM1)
>> print(mod.cov)
>>
>> I <- SEM$I1
>> M <- SEM$M1
>> R <- SEM$R1
>>
>> model <- specify.model()
>> Z -> M
>> Z -> I
>> Z -> R
>> M <-> M
>> I <-> I
>> R <-> R
>> Z <-> Z
>>
>> sem.mod <- sem(model, mod.cov, N=109)
>> summary(sem.mod)
>>
>>
>>
>> All vectors have a length of 109.
>>
>>
>> Thank you for your help once again.
>>
>> Best wishes,
>> Luba
>>
>>
>>
>> -----Urspr?ngliche Nachricht-----
>> Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
>> project.org] Im Auftrag von Jarrett Byrnes
>> Gesendet: Montag, 20. Juli 2009 18:25
>> An: Stein, Luba (AIM SE)
>> Cc: r-help at r-project.org
>> Betreff: Re: [R] Another SEM question
>>
>> Luba,
>>
>> If you could provide the code you ran, perhaps the listserv can be of
>> help.
>>
>> On Jul 20, 2009, at 7:55 AM, Stein, Luba (AIM SE) wrote:
>>
>>> Hello,
>>>
>>> I use the function sem the following way
>>> sem.mod <- sem(model, mod.cov, N=109) where the variables are
>>> modelled:
>>>
>>> Z -> M
>>> Z -> I
>>> Z -> R
>>> M <-> M
>>> I <-> I
>>> R <-> R
>>> Z <-> Z
>>>
>>> The output is
>>> ...
>>>
>>> Normalized Residuals
>>> Min. 1st Qu. Median Mean 3rd Qu. Max.
>>> -7.3300 -0.2750 -0.2670 -0.1290 -0.0369 9.0300
>>>
>>> Parameter Estimates
>>> Estimate Std Error z value Pr(>|z|)
>>> 0.0021625 0.00017037 12.693 0 M <--- Z
>>>
>>> Iterations = 13
>>>
>>>
>>> In "Structural Equation Modeling With the sem Package in R" by John
>>> Fox is stated that there should be an output for each external
>>> variable.
>>>
>>> Where is my fault, that I receive the output only for the first
>>> variable?
>>>
>>>
>>> Thanks for your help,
>>> Luba
>>>
>>>
>>>
>>>
>>>
>>> 	[[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at r-project.org 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.
>>
>> ______________________________________________
>> R-help at r-project.org 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.
>
> ______________________________________________
> R-help at r-project.org 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.