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Re: st: sem - is it possible to drop error terms?


From   Stas Kolenikov <skolenik@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: sem - is it possible to drop error terms?
Date   Tue, 12 Mar 2013 14:36:32 -0500

Sometimes, you have to force -sem- to run, and frankly I don't know of
all the best ways to do that. (Just posted something on statalist a
few hours ago, did not run that well, either.)

-- Stas Kolenikov, PhD, PStat (SSC)
-- Senior Survey Statistician, Abt SRBI
-- Opinions stated in this email are mine only, and do not reflect the
position of my employer
-- http://stas.kolenikov.name



On Tue, Mar 12, 2013 at 2:17 PM, Jacob Felson <felsonj@gmail.com> wrote:
> Stas,
>
> Thanks!  Its strange -- when I try to run a basic behavior genetic
> model (ACE) using Stata's sem command, I immediately receive an error
> saying there are too many latent variables and the model is not
> identified.  But this model is definitely identified -- at least
> theoretically.  Model is here:
> http://www.biomedcentral.com/1471-2202/5/49/figure/F1?highres=y
>
> Sorry to bother you.  Any help you could provide is much appreciated.
>
> Sincerely,
>
> Jacob Felson
>
>
>
> On Tue, Mar 12, 2013 at 2:59 PM, Stas Kolenikov <skolenik@gmail.com> wrote:
>> Jacob,
>>
>> you can constrain the variance of these error terms to zero with
>> -variance()- option of -sem-.
>>
>> -- Stas Kolenikov, PhD, PStat (SSC)
>> -- Senior Survey Statistician, Abt SRBI
>> -- Opinions stated in this email are mine only, and do not reflect the
>> position of my employer
>> -- http://stas.kolenikov.name
>>
>>
>>
>> On Tue, Mar 12, 2013 at 1:53 PM, John Antonakis <John.Antonakis@unil.ch> wrote:
>>> Hi Jacob:
>>>
>>> You need to be much more specific about what specific model you wish to test
>>> (write-out equations or syntax). Most probably don't know what ACE is:
>>>
>>> http://www.stata.com/support/faqs/resources/statalist-faq/
>>>
>>> Best,
>>> J.
>>>
>>> __________________________________________
>>>
>>> John Antonakis
>>> Professor of Organizational Behavior
>>> Director, Ph.D. Program in Management
>>>
>>> Faculty of Business and Economics
>>> University of Lausanne
>>> Internef #618
>>> CH-1015 Lausanne-Dorigny
>>> Switzerland
>>> Tel ++41 (0)21 692-3438
>>> Fax ++41 (0)21 692-3305
>>> http://www.hec.unil.ch/people/jantonakis
>>>
>>> Associate Editor
>>> The Leadership Quarterly
>>> __________________________________________
>>>
>>>
>>> On 12.03.2013 19:30, Jacob Felson wrote:
>>>>
>>>> I'm wondering if its possible to drop the error terms that are
>>>> included by default in sem models.  I've searched in the manual and
>>>> online but I can't find any indication that this is possible.  I
>>>> imagine its not, but I wanted to check with the experts to make sure.
>>>>
>>>> (I'm estimating a behavior genetic model with data on MZ and DZ twins
>>>> -- the so-called ACE model.)
>>>>
>>>>
>>>> Thank you,
>>>>
>>>>
>>>> Jacob Felson
>>>> *
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>>>
>>>
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>> *
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>
>
>
> --
> Jacob Felson
> *
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*
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