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Re: st: error message after dtobit


From   Richard Williams <Richard.A.Williams.5@ND.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: error message after dtobit
Date   Sun, 07 May 2006 20:47:12 -0500

At 08:15 PM 5/7/2006, Richard Williams wrote:
You often need to use version control on the estimation command with user-written post-estimation commands. Stata changes something and these older post-estimation commands get zapped. Try this:
To follow up on that a bit: If you type -help version- , you find that if you set version to less than 9,

"14. Commands ologit and oprobit revert to pre-Stata 9 logic in how e(b) and e(V) are stored. Results were stored in two equations, with all cut points stored in the second.

"15. Commands tobit and cnreg revert to pre-Stata 9 logic in how e(b) and e(V) are stored. Results were stored in a single equation containing both coefficients and the ancillary variance parameter."

So, my guess is that older user-written post-estimation commands written to work with ologit, oprobit, tobit and cnreg may encounter problems in Stata 9. There may be others. Unfortunately, the fact that the user-written command used version control does not help, because it expects the results stored in e() to be in a certain format. This seems to affect the user-written commands dtobit, margeff, and no doubt many others.

The solution is to run the estimation command with version control, e.g.

version 8.2: ologit y x1 x2 x3

Perhaps the authors will eventually update their programs, or if you are daring you can try to make the modification yourself. Also, some authors offer different versions of their programs for different versions of Stata (e.g. the spost programs of Long & Freese; Roger Newson and Nick Cox are also among the kindly authors who do this).

It is also possible sometimes just to write a little code in your program that checks for the version of Stata being used and then adjusts accordingly. When it works, this saves the hassle of having multiple versions of a program floating around. Or, you might be able to come up with a more general coding that works regardless of the version of Stata used.


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Richard Williams, Notre Dame Dept of Sociology
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