New subject: Gretl-users Digest, Vol 30, Issue 14

Friday, 27 October 2006

Thank you for your reply.

The point is that I'd like to constrain the fitted values (and not the
observed ones) of the dependent variable.

The problem is that my depedent variable cannot "physically" (i.e., in real
world situations) extrapolate a certain range of values (thus all my
observed values lie within this range) but when I run the regression some of
the fitted values are, in fact, outside this range (although the general fit
of the model is good). So I need a kind of Tobit model, but I need to
specify not only the lower bound but also the upper bound of the range. The
Tobit command in GRETL constrains the lower bound to zero (whenever the
fitted values are negative), but it does not specify an upper bound (and it
does not allow me to specify a lower bound other than zero).

Best regards,

Thiago

2006/10/27, gretl-users-request(a)ricardo.ecn.wfu.edu <
gretl-users-request(a)ricardo.ecn.wfu.edu&gt;:
...

 Message: 1
 Date: Thu, 26 Oct 2006 18:02:59 -0400
 From: James Wells <jlwells(a)panix.com&gt;
 Subject: Re: [Gretl-users] censored regression
 To: Gretl list <gretl-users(a)ricardo.ecn.wfu.edu&gt;
 Message-ID: <45413093.1090202(a)panix.com&gt;
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 Just a thought, but can transform your dependent variable so that the
 minimum is zero?  E.g., suppose your observed values of Y are 3, 5, and
 8 so in the console, do "genr newdepvar = Y - 3"

 Thiago Marzagão wrote:
 > I'd like to constrain my dependent variable (which is quantitative and
 > continuous) estimates to lie within a certain range (say, A and Z). Is
 > there any way to do that with GRETL? (Tobit command constrains the
 > lower bound to zero, but I think it does not allow me to specify an
 > upper bound or an alternative lower bound)
 >
 > Thank you,
 >
 > Thiago Marzagão
 > ------------------------------------------------------------------------ 

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Re: Gretl-users Digest, Vol 30, Issue 14