[Limdep Nlogit List] Standarized tobit coefficients

Macario Rodríguez Entrena macario.ent at gmail.com
Mon Jan 4 02:39:11 EST 2010

Dear Limdep Users:

I am trying to obtain standardized tobit coefficients per Long (1997).
Initially, I calculated the standardized tobit coefficients after
estimation per Roncek (1992) as follows:

Bks(standarized)=Bk (Sigma k / Sigma y*)

Long (1997) criticized this approach because sigma is conditional on x.
He suggests instead to use the unconditional variance of y* computed
with the quadratic form:

(Sigma^ y*)2=B^' Var^(x) B + (Sigma^ E)2

where Var^(x) is the estimated covariance matrix among the x's and
(Sigma^ E)2 is the ML estimate of the variance of E.

Unfortunately, I am having difficulty with transferring this formula into
I hope someone on the list could offer some help.

Thanks in advance

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