Notice: On March 31, it was **announced** that Statalist is moving from an email list to a **forum**. The old list will shut down on April 23, and its replacement, **statalist.org** is already up and running.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

From |
Roger Cremades Rodeja <ecosafor@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Re: A fractional logit can't converge. Anyway, backed up results are useful for mfx? how? |

Date |
Thu, 8 Mar 2012 16:12:08 +0100 |

Dear Marteen and Nick, I am extremely grateful for your help and clarity. Using -technique(bhhh)- it worked perfectly. Marteen, yes I do have a big spike, you were right! I use proportion data of 1,300 households, but most of them have a 0 in my dep var, so I though it was because of that, as in my other two models just change the dep var and it has more variation. Nick, I meant logit (I spelt tobit wrongly). Bless you!! Roger El día 8 de marzo de 2012 14:29, Maarten Buis <maartenlbuis@gmail.com> escribió: > On Thu, Mar 8, 2012 at 1:14 PM, Roger Cremades Rodeja > <ecosafor@gmail.com> wrote: >> I am using fractional tobit "glm depvar indepvar, link(logit) >> family(binomial) vce(robust)". I successfully used it in other two models, >> but in this case after some iterations Stata says "backed up" and cannot >> converge, then I create a table with the results (outreg), and still appears >> a resulting table with results that are consistent with my other two models, >> do those results makes statistical sense? > > They make no sense, so don't look at them and certainly don't try to > publish anything with them. > >> I want to create then elasticities with "mfx" but I can't because the >> model did not converge, if those results produced with outreg (previous >> line) make a bit of sense, how can I create elasticities with them using >> Stata? > > Don't do that. > >> Also, after typing the command appear "note: perc_mod_com has noninteger >> values", I do not understand why, as I think proportion variables should be >> 0 to 1. > > That message makes sense: remember that -glm- is a general purpose > program that can be "tricked" into estimating a fractional logit. > >> Following previous emails in Statalist, I tried delete some >> variables and I still couldn't solve it, OLS do not reject any variable, the >> model do not work trying to delete indep variables one by one, and I am >> trying more and more combinations, but it still does not work. > > I would look for some form of perfect prediction. This becomes more > likely if you have a very large spike in the dependent variable > (typically at 0 or 1) or a small sample size. > >> Please somebody knows if this analysis can be carried on using another >> sofware? I need these results.. > > I think it is a problem with your data not your software. > > -- Maarten > > -------------------------- > Maarten L. Buis > Institut fuer Soziologie > Universitaet Tuebingen > Wilhelmstrasse 36 > 72074 Tuebingen > Germany > > > http://www.maartenbuis.nl > -------------------------- > > * > * 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/ * * 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/

**References**:**st: Re: A fractional logit can't converge. Anyway, backed up results are useful for mfx? how?***From:*Roger Cremades Rodeja <ecosafor@gmail.com>

**Re: st: Re: A fractional logit can't converge. Anyway, backed up results are useful for mfx? how?***From:*Maarten Buis <maartenlbuis@gmail.com>

- Prev by Date:
**Re: st: Re: A fractional logit can't converge. Anyway, backed up results are useful for mfx? how?** - Next by Date:
**re: st: CI interval in ANOVA summary table** - Previous by thread:
**Re: st: Re: A fractional logit can't converge. Anyway, backed up results are useful for mfx? how?** - Index(es):