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| From | David Youngberg <davidyoungberg@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: heteroskedasticity correction with xttobit |
| Date | Sun, 20 May 2012 18:06:41 -0400 |
Austin, The outcome variable is a constructed variable--patent quality--which ranges from 0 to 1000 (lower and upper bounds, respectively). The variable of interest is the labor mobility of scientists and engineers (proportion who changed jobs in the last year). The editor of the journal I submitted to specifically requested using tobit so I'm inclined to stick with that, if possible. David On Thu, May 17, 2012 at 9:47 AM, Austin Nichols <austinnichols@gmail.com> wrote: > David Youngberg <davidyoungberg@gmail.com>: > vce(boot) does not "correct" for heteroskedasticity since > xttobit assumes i.i.d. normal errors independent of normal random effects. > I.e. you are working with untenable assumptions, in all likelihood. > What is the outcome variable and what is the explanatory variable of interest? > What kind of censoring is involved? > Often there are preferable alternatives to tobit models. > > On Thu, May 17, 2012 at 9:10 AM, David Youngberg > <davidyoungberg@gmail.com> wrote: >> Dear Statalisters, >> >> I'm running Stata 10 and need to run xttobit with a heteroskedasticity >> correction. Robust isn't an option. I've tried running vce(boot) but >> it's taking too long (after 36 hours, Stata wasn't done with the first >> rep). I'm running about 150,000 observations, have 4 GB RAM, and >> processor's 2.8 GHz. >> >> Looking for alternative methods of correction with xttobit or if >> upgrading Stata/computer would make the difference. >> >> Thanks, >> David > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ -- Assistant Professor of Economics Bethany College http://dyoungberg.com http://blogs.worthpublishers.com/seetheinvisiblehand/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/