Dear statalisters,
i am asking your advice on how to estimate a system of equations in the
presence of an adding-up contraint.
My problem is perhaps similar to that tackled by Poi (2002), SJ, 2(4):
403-410, but I'm not sure how far I can stretch the comparison,
and would like to avoid shooting at a fly using a cannon.
Here are the details of my problem.
The dependent variables are relative frequencies: pi_1, pi_2, ..., pi_7,
which sum up to one.
I need to estimate the *same* model for each pi_i (i = 1,...7). The model is
linear and simple enough:
pi_i = alpha_i + beta1_i * X1 + ... + betak_i * Xk (i=1,...,7)
The difficulty is that I want to obtain predicted values that add up to one.
Is there a way of achieving this by using sureg? Do I have to venture into
ml programming?
Any suggestions will be greatly appreciated.
Giovanni
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Giovanni VECCHI
Dipartimento di Economia e Istituzioni
Università di Roma "Tor Vergata"
Via Columbia, 2
00133 Roma
Italy
voice + 39 06 7259 5730
fax + 39 06 2020 500
email giovanni.vecchi@uniroma2.it
webpage http://www.economia.uniroma2.it/vecchi.htm
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