[Limdep Nlogit List] Heckit model

[M Goergen]

Dear Randall

Thank you for your reply.

I have 29 observations that equal one and 85 that are equal to zero. As the
selection equation contains a constant and just one variable, I am surprised 
that I do not have enough degress of freedom. I have even recoded the dependent
variable in the probit, so that I have 85 observations which equal one, but
this still does not make a difference.

Marc


Quoting Randy Kesselring <RANDYK at astate.edu>:

> Marc,
> 
> When you run the probit, it uses all of your observations and you have a
> sufficient number to accomplish that estimation.  When you use the
> select command it selects only the observations for the variable on the
> left-hand-side of the probit that equal one.  This significantly reduces
> the number of observations, and in your case, there are not enough
> observations to accomplish the estimation.
> 
> Randall G. Kesselring
> Professor of Economics
> Arkansas State University
> Phone: 870-680-8467
> Randyk at astate.edu
> -----Original Message-----
> From: limdep-bounces at limdep.itls.usyd.edu.au
> [mailto:limdep-bounces at limdep.itls.usyd.edu.au] On Behalf Of Marc
> Goergen
> Sent: Friday, November 30, 2007 1:44 PM
> To: limdep at limdep.itls.usyd.edu.au
> Subject: [Limdep Nlogit List] Heckit model
> 
> Dear all
> 
> I am trying to run a Heckman selection model. The probit runs well, but
> when
> I try to run the linear regression using the 'select' command I get
> "error
> message 201: SELECT - selection leaves insufficient degrees of freedom".
> What is the cause of this?
> 
> Best wishes,
> 
> Marc 
> 
> 
> 
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-- 
Prof. Marc Goergen
Sheffield University Management School (SUMS)
Sheffield University
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UK

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European Corporate Governance (ECGI) Research Associate
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SSRN author page:
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