Re: [Gretl-devel] gretl bug: ordered probit model
On Mon, 9 Oct 2017, Artur T. wrote:
> However, I was thinking: can lagging the constant ever make
sense, in any
> situation? Shouldn't const(-1) be a no-op?
I cannot think of any situation where const(-1) does make sense at all. It
was just by coincidence included in a list of regressors I worked with.
Nevertheless, I guess it would be good if gretl would return an error in this
case. Wouldn't it make sense to pre-check whether there is any series (apart
from the intercept) with variance=0?
The problem is not as simple, as we need to guard against "constants in
disguise", as for example exhaustive sets of dummies. The more I think
about this, the more I'm convinced we should throw an error at any attempt
to create lags of "const".
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Riccardo (Jack) Lucchetti
Dipartimento di Scienze Economiche e Sociali (DiSES)
Università Politecnica delle Marche
(formerly known as Università di Ancona)
r.lucchetti(a)univpm.it
http://www2.econ.univpm.it/servizi/hpp/lucchetti
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