[Limdep Nlogit List] re: panel tobit model

[ecptq at bath.ac.uk]

Dear Professor Greene,

Thanks a lot for your quick reply. I double checked the grpsize 
variable, it is correct, although this is an unbalance panel.

The value range of the left hand side variable is from 0 to 12, and the 
value '0' indicates a good body shape. As to other values, the more 
they are away from'0', the worse is the body shape.

So I fit the (random-effects) tobit model with the default censoring 
specification which is left censoring at 0.0, as the estimation of a 
fixed effects Tobit model is problematic as argued in your paper.

Based on this, can you kindly suggest me (i) whether the tobit is the 
right model to select; (ii), if so, the random-effects is the only 
option, isn't it?

Thanks a lot.

Best regards
Tian Qiu

Dear Ms. Qui:  Assuming the grpsize variable is set up correctly, then
(1) No, with only two iterations, the RE model has not been estimated and
(2) You should rethink the random effects specification.  This outcome is
not due to a failure of the program. It occurs if the RE model is the wrong
model for the data.
Regards,
Bill Greene

************************************************
Professor William Greene
Department of Economics
Stern School of Business
New York University
44 West 4th St., Rm. 7-78
New York, NY   10012
Ph. 212.998.0876
Fax. 212.995.4218
URL. http://www.stern.nyu.edu/~wgreene
Email. wgreene at stern.nyu.edu
************************************************

----- Original Message -----
From: ecptq at bath.ac.uk
Date: Sunday, May 20, 2007 3:24 pm
Subject: [Limdep Nlogit List] panel tobit model


[Hide Quoted Text]
> Hi, everyone,
>
> I am running the random-effects tobit as follows:
>
> tobit;lhs=body;rhs=one,X;pds=grpsize$
>
> It comes the results with:
> Error:   806: Line search does not improve fn. Exit iterations. Status=3
> and the table shows iterations completed = 2.
>
> Are the results of this random-effects tobit still reliable, and is
> there anything I can do about it?
>
> Thanks in advance.

-- 
Miss Tian Qiu
Department of Economics and International Development
University of Bath
Tel.: (01225) 384864