[R] SEM error

[Jarrett Byrnes]

I have often found this to happen if the scale of one variable is  
orders of magnitude different than the scale of other variables.  Have  
you tried inspecting the covariance matrix and log transforming any  
such variables?

On Feb 22, 2010, at 8:14 AM, Uwe Ligges wrote:

>
>
> On 20.02.2010 08:51, Dan Edgcumbe wrote:
>> I'm trying to do some confirmatory factor analysis on some data. My  
>> SEM
>> model solves in 22 iterations, but when I try to look at the  
>> modification
>> indices, using mod.indices, I get the following error message:
>>
>> Error in solve.default(hessian) :
>>   system is computationally singular: reciprocal condition number =
>> 4.40283e-18
>>
>> What does this mean?
>
> That the method you apply tries to invert some object called  
> "hessian" (maybe a hessian? ;-)) but fails since a singular matrix  
> cannot be inverted. Perhaps (as I often found for people doing sem  
> analyses) you have less observations than parameters to estimate or  
> only certain combinations for some factors?
>
> Uwe Ligges
>
>
>
>
>
>>
>> Many thanks,
>>
>> Dan
>>
>> 	[[alternative HTML version deleted]]
>>
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>
> ______________________________________________
> 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.