Hi there,
I estimate the following structural equation and test for overidentifying restrictions:
cons 1 ([x1]L1.x1 + [x1]L1.x3 + [x1]L1.x4 + [x2]L1.x2 + [x2]L1.x5 + [x2]L1.x6) = 0
reg3 (y x1 L1.x1 x2) (x1 L1.x1 L1.x3 L1.x4 ind*) (x2 L1.x2 L1.x5 L1.x6 ind*), small dfk l(95) cons(1)
overid
but, disappointingly enough, I get the message:
L.SAL_d invalid name
st_view(): 3500 invalid Stata variable name
overidreg3(): - function returned error
<istmt>: - function returned error
r(3500);
I make an educate guess and generate lagged values instead of using lagged operators and rerun the exercise, as follows:
cons 1 ([x1]Lx1 + [x1]Lx3 + [x1]Lx4 + [x2]Lx2 + [x2]Lx5 + [x2]Lx6) = 0
reg3 (y x1 Lx1 x2) (x1 Lx1 Lx3 Lx4 ind*) (x2 Lx2 Lx5 Lx6 ind*), small dfk l(95) cons(1)
overid
only to get another message:
*: 3900 unable to allocate real <tmp>[14356,14356]
overidreg3(): - function returned error
<istmt>: - function returned error
r(3900);
I am in the dark here and any suggestions why this is happening are most welcome.
Also, if this problem is indeed due to an OS limitation and cannot be circumvented, then is it safe to run ivreg2 regressions and test overid separately? I went through previous Statalist posts and have read that it is possible. Specifically, Mark Schaffer noted "you don't end up in exactly the same place, but it's close" (http://www.stata.com/statalist/archive/2004-09/msg00234.html). Is "close" good enough? Doesnt this depend on whether the structural system is estimated using 2SLS or 3SLS? Also,
many thanks, Demetris Christodoulou (Sydney)
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