Re: st: Standardized tobit coefficients

[Richard Williams <Richard.A.Williams.5@ND.edu>]

At 08:32 PM 10/1/2008, SEVIGNY, ERIC wrote:
> Dear Stata 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:
>
> foreach var of varlist x1 x2 x3 etc. {
>       quietly sum `var'
>       display as result "beta* `var' =" (_b[`var']*r(sd))/.5697083)
> }
>
> where .5697083 is sigma reported by the tobit model.
>
> 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, where r_(y*)^2=B'Var(x)B+s_e^2 (which I read as
> the unconditional variance of Y* equals the variance/covariance matrix
> of x plus an error term). Unfortunately, I am having difficulty with
> transferring this formula into Stata. I am unfamiliar with using and
> accessing matrix information, and hope someone on the list could offer
> some help.
>
> Thanks in advance.
>
>
> Eric L. Sevigny
You can probably use Long & Freese's -listcoef- command with the 
-std- option.  From within Stata, type

findit spost9

Long & Freese's excellent book describing this and several other 
commands can be found at

http://www.stata.com/bookstore/regmodcdvs.html





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Richard Williams, Notre Dame Dept of Sociology
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