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From |
"Verkuilen, Jay" <JVerkuilen@gc.cuny.edu> |

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

Subject |
RE: st: How do I test that two subsample have different coefficient of variation? |

Date |
Thu, 10 Jul 2008 17:53:32 -0400 |

One other point: Many seemingly ratio scale variables are actually log-interval, e.g., gas mileage, which can be equally well represented as miles per gallon or gallons per mile. There is a very nice FAQ on this on the SAS web page: ftp://ftp.sas.com/pub/neural/measurement.html -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Verkuilen, Jay Sent: Thursday, July 10, 2008 5:42 PM To: statalist@hsphsun2.harvard.edu Subject: RE: st: How do I test that two subsample have different coefficient of variation? Peter Lachenbruch wrote: >Perhaps a naïve approach would be to bootstrap the cv with a few thousand reps. An obvious problem arises if the mean is near 0. >I suspect one should restrict this to positive random variables, but I have no theory to go on. Seems right to me. CV is meaningful for a ratio scale variable (e.g., mass, time, distance) but not an interval one (e.g,. Celsius temperature, utility). While it is, of course, possible to define a signed ratio scale, the vast majority of them are non-negative. * * 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**:**RE: st: How do I test that two subsample have different coefficient of variation?***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**References**:**st: How do I test that two subsample have different coefficient of variation?***From:*Antonio Vezzani <antonio.vezzani@uniroma2.it>

**Re: st: How do I test that two subsample have different coefficient of variation?***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**Re: st: How do I test that two subsample have different coefficient of variation?***From:*"Austin Nichols" <austinnichols@gmail.com>

**RE: st: How do I test that two subsample have different coefficient of variation?***From:*"Lachenbruch, Peter" <Peter.Lachenbruch@oregonstate.edu>

**RE: st: How do I test that two subsample have different coefficient of variation?***From:*"Verkuilen, Jay" <JVerkuilen@gc.cuny.edu>

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