On Sat, 3 Oct 2009, Nikil van Wijk wrote:
Using a panel data set in Gretl, I'm trying to obtain a
F-statistic for country (fixed or random) effects and a
F-statistic for time (fixed or random) effects. Gretl offers the
possibility to generate both time and unit (country) dummies in
the 'add' menu, but in the 'model'-'panel'-'fixed or random
effects' menu, the only option is 'include time dummies'. (not
unit dummies).
The statistic for the effect of country (dummies) cannot be obtained by
including all dummies in the dataset, because then they are 'Omitted
due to exact collinearity'.
Any ideas on how to solve this?
Use gretl's fixed-effects estimator and the F-test for the country
effects is printed automatically.
Besides that, if you're puzzled by the message about exact
collinearity, read up on dummy variables in any introductory
econometrics textbook.
Allin Cottrell