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From |
"Lachenbruch, Peter" <Peter.Lachenbruch@oregonstate.edu> |

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

Subject |
RE: st: RE: Converting a continuous var into a binary var |

Date |
Tue, 7 Jul 2009 09:58:42 -0700 |

I generally agree with this. There was an old article in 1961 Biometrics by Cochran and Hopkins who noted that about 90% of the information was retained if you cut the variable at 6 points (I think equidistant, but my recollection may be faulty). I am particularly interested in this since I'm looking at some data for a multiple imputation in which we would like the continuous variables to be approximately normally distributed. Many are not. In looking for transformations to normality (boxcox), nothing seems to work. So my solution has been to group them into 5 or 6 categories and use ologit for imputation. The problem has been a huge excess of zeros. Tony Peter A. Lachenbruch Department of Public Health Oregon State University Corvallis, OR 97330 Phone: 541-737-3832 FAX: 541-737-4001 -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox Sent: Tuesday, July 07, 2009 9:52 AM To: statalist@hsphsun2.harvard.edu Subject: RE: st: RE: Converting a continuous var into a binary var I am happy that any Stata Journal columns of mine are useful, but that really wasn't the point I was making. Dichotomising continuous variables throws away information. Usually that's a bad, or at least a dubious, idea. Nick n.j.cox@durham.ac.uk Pancho Villa On Tue, Jul 7, 2009 at 9:35 AM, Nick Cox<n.j.cox@durham.ac.uk> wrote: > That aside, the mechanics of how to do this have been thoroughly > ventilated, but its meaning has not been. Yes, I'm reading the column on *for*, which seems like written with me in mind. I'm one of those who've postponed learning about macros, etc. * * 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: Converting a continuous var into a binary var***From:*Pancho Villa <panchovillainnyc@gmail.com>

**st: RE: Converting a continuous var into a binary var***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: RE: Converting a continuous var into a binary var***From:*Pancho Villa <panchovillainnyc@gmail.com>

**RE: st: RE: Converting a continuous var into a binary var***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: RE: Converting a continuous var into a binary var***From:*Pancho Villa <panchovillainnyc@gmail.com>

**RE: st: RE: Converting a continuous var into a binary var***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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