st: estimating production function

["Martinez San Roman, Valeriano" <valeriano.martinez@unican.es>]

Dear Stata users,

I hope you can help me. I am trying to estimate a cobb-douglas
production function (Y=X1^a*X2^b*X3^c*....) using panel data with fixed
effects.

I am using the log of the production function as my functional form,
that is, Ln(Y) = aLn(X1) + bLn(X2) + cLn(X3)+....

And I have to assume that we have constant returns to scale, in other
words, the sum of the exponentials must be equal to 1 (a+b+c+...=1)

Is there a command to restrict the sum of exponentials to be equal to 1.
How can I do it?

Thank you very much,
Valeriano



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