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From |
Steven Samuels <sjhsamuels@earthlink.net> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: How low can the percentage of uncensored cases be in heckprob? |

Date |
Tue, 11 Nov 2008 16:17:48 -0500 |

-Steve Refs:

http://www.psychosomaticmedicine.org/cgi/content-nw/full/66/3/411/ On Nov 11, 2008, at 12:15 PM, Maarten buis wrote:

--- "Tyler, Margaret C D" <margaret-tyler@uiowa.edu> wrote:In the example in the Stata reference -H heckprob, there are 95 total and 59 uncensored observations, so 62% are uncensored. In my own situation I have only about 19% uncensored. Is it still appropriate to use heckprob for my analysis? I have run the equations and gotten what seem to be valid results. rho is non-significant.You are obviously pushing your luck with that many censored cases. It is no longer very popular to make statements like you need at least N observation or p% uncensored cases for technique t to be appropriate (whatever appropriate may mean). So I don't think you will get the answer you are looking for. However, what you can do is run some simulations and see how well (or bad) your estimator behaves with a small number of uncensored cases. At the last Summer North American Stata Users' Group meeting I gave a talk on using Stata for doing this type of simulations, you can get the materials from: http://ideas.repec.org/p/boc/nsug08/14.html Hope this helps, Maarten ----------------------------------------- Maarten L. Buis Department of Social Research Methodology Vrije Universiteit Amsterdam Boelelaan 1081 1081 HV Amsterdam The Netherlands visiting address: Buitenveldertselaan 3 (Metropolitan), room N515 +31 20 5986715 http://home.fsw.vu.nl/m.buis/ ----------------------------------------- * * 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/

**Follow-Ups**:**Re: st: How low can the percentage of uncensored cases be in heckprob?***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**References**:**Re: st: How low can the percentage of uncensored cases be in heckprob?***From:*Maarten buis <maartenbuis@yahoo.co.uk>

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