Following the first code-steps in Gretl provided by Professor Schreiber and
a SAS code provided by Professor Angrist (again, many thanks to both
Professors for your attention), I have performed a solution in R (sorry, at
the moment I'm more familiar with this language) to this issue.
The code is weird, but is written with the aim to show the step-by-step
process and check the intermediate results.
If someone is interested in this topic, the data and my code could be
Please, be sure that any error is mine. I would be grateful for
suggestions, improvements and corrections.
Thanks a lot for your attention and best regards
University of Alicante