[Limdep Nlogit List] Panel Data Analysis - Fixed or Random Effect

[Prof. Saravanan]

Hi Members,
I am a new entrant to this group. I have a query: How one choose between
fixed or randome effect in the context of panel data. Further can you
suggest me some resource / books (non-technical ones) to enhance my
knowledge in panel data analysis.
Thanks in advance,
Saravanan
Goa, INDIA

On Thu, Aug 20, 2009 at 4:54 PM, William Greene <wgreene at stern.nyu.edu>wrote:

> M. Karakaplan.
> The difference in the number of iterations results because the
> programs are using different algorithms - Stata uses Newton's
> method and Limdep uses BFGS. You did not report the command you
> used, so it is not clear that you actually were fitting the
> same model with the two programs. But, assuming you were, I suspect
> the following. The estimator should converge in about 10 iterations
> or so in Limdep, 5 or so with Stata. Since you went to 27 with
> Stata and never did actually converge with Limdep, I would guess
> that neither program actually estimated a model. With this many
> iterations, with this model, it is very likely that you have a
> serious data problem. The answers produced by both programs are
> probably nonsense.  In order to judge more completely, I would
> have to see your output.
> One final point, Stata uses a different parameterization of the
> model than Limdep. The asymmetry parameter that characterizes the
> inefficiency is set up in Limdep according to the original Aigner,
> Lovell and Schmidt specification. The same model is parameterized
> in Stata according to the model reformulated by Tim Coelli in his
> Frontier 4.1 program. It is a 1 to 1 reparameterization, so it
> should not affect the results, but optimization in an ill behaved
> data set can be affected by the normalization in the model.
> /Bill Greene
>
>
>
> ----- Original Message -----
> From: "M.U. Karakaplan" <karakaplan at tamu.edu>
> To: limdep at limdep.itls.usyd.edu.au
> Sent: Thursday, August 20, 2009 4:58:04 AM GMT -05:00 Columbia
> Subject: [Limdep Nlogit List] Different results in Frontier Analysis in
> Limdep and Stata
>
> I run exactly the same frontier model in Limdep and Stata, but I get
> different results:
>
> The descriptive statistics are the same
> The number of observations and parameters are the same.
> The coefficients are very similar, but not the same.
> The numbers of iterations are different: Limdep: 101 iterations; Stata:
> 27 iterations.
> When I set the maximum iterations in Limdep to be the same of Stata, the
> difference gets bigger.
> When I set the maximum iterations to 200 in Limdep, it runs only 125
> iterations and the difference between the results gets very very small,
> but they are still not the same.
>
> How can I get the same results? What is this difference between Limdep
> and Stata results due to? Is it related to confidence level? If yes, is
> there a way to change it in Limdep?
>
> _______________________________________________
> Limdep site list
> Limdep at limdep.itls.usyd.edu.au
> http://limdep.itls.usyd.edu.au
> _______________________________________________
> Limdep site list
> Limdep at limdep.itls.usyd.edu.au
> http://limdep.itls.usyd.edu.au
>



-- 
P.Saravanan
Associate Professor &
Chairman Finance Area
Goa Institute of Management,
Ribandar, Goa 403 006
INDIA
Phone:+91-832-2490351(Direct)
          +91 -832-2490300
Fax:      +91-832-2444136
Mobile: +91-9881722515
Alternate Email:ps at gim.ac.in <Email%3Aps at gim.ac.in>
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+= +=+
Say not always what you know, but always know what you say.
Claudius; 10 BC-AD 54, Roman Emperor
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+