
From  "Brian P. Poi" <bpoi@stata.com> 
To  Statalist Statalist <statalist@hsphsun2.harvard.edu> 
Subject  Re: st: ivprobit error message, outreg, lnsigma and athrho 
Date  Thu, 30 Nov 2006 11:04:48 0600 (CST) 
On Thu, 30 Nov 2006, Nirina F. wrote:
Are you using the "from()" option to specify initial values? If so, then you need to specify a row vector with 126 elements.Hello List, 1 I am running ivreg and it works fine but I would like to run ivprobit (as I have binary choice for my dependent variable) and it gives me the following error: inital vector: matrix must be dimension 126 r(503). I don't know what to do to correct it.
lnsigma and athrho are transformations of sigma and rho that are used in the estimation process. What you care about are sigma and rho, reported below lnsigma and athrho in the output. Sigma is the variance of the reducedform equation for the endogenous regressor. The more interesting parameter is rho, which is the correlation between the errors in the probit equation and the reducedform equation for the endogenous regressor. Rho being equal to zero is equivalent to saying that the variable you suspect to be endogenous is in fact exogenous; in other words, if the estimated rho is insignificant, then we cannot reject the null that there is no endogeneity issue and a plain probit regression could be used.3Can somebody explain me the interpretation of the lnsigma and athrho please? Thanks a lot in advance, Nirina
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