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From |
"Feiveson, Alan H. (JSC-SK311)" <alan.h.feiveson@nasa.gov> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: RE: fractional logit? |

Date |
Fri, 1 Feb 2008 13:19:20 -0600 |

ALso consider using a beta distribution to model the fractions - ssc describe betafit al Feiveson -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Verkuilen, Jay Sent: Friday, February 01, 2008 12:47 PM To: statalist@hsphsun2.harvard.edu Subject: st: RE: fractional logit? Viktor Slavtchev wrote: >>I have individual data where people report the share of time they spend in five distinct activities. People can do more than one activity every day: first jogging, then go to work, then shopping, whatever. That is, there are five observation per ID individual. Actually, the ID is the (each person's) day. I wish to explore the individual characteristics determining the share of time spent for each activity. As the dependent variable is a share [0;1] I was thinking about fractional logit. In Stata it would be (I guess): glm y x, family(binomial) link(logit). However, I am not clear whether fractional logit can be applied on the original data, or the data have first to be transformed in some way. Moreover, in doing -glm- live above I implicitly assume that each observation is independent which is definitely not true. Does anybody know some solution?<< Yes, you are correct that there are notable dependencies among the variables caused by the sum constraint. Take a look at the book by John Aitchison, Compositional Data Analysis. The original edition is 1986 but it was republished in 2003 with some additions. Feel free to drop me a line, I'm interested in this problem. Jay * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: RE: RE: RE: fractional logit?***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**st: RE: RE: RE: fractional logit?***From:*"Verkuilen, Jay" <JVerkuilen@gc.cuny.edu>

**References**:**st: fractional logit?***From:*Viktor Slavtchev <viktor.slavtchev@uni-jena.de>

**st: RE: fractional logit?***From:*"Verkuilen, Jay" <JVerkuilen@gc.cuny.edu>

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