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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

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

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

Date |
Fri, 11 Jul 2008 17:18:59 +0100 |

I don't doubt you can often get away with the cv when the implicit assumptions are not too unrealistic on the whole. The same applies to almost all statistical methods. Yes, the Kelvin scale plays some part in climatology, and could be used more, but it's not conventional for the contexts I was quoting. Nick n.j.cox@durham.ac.uk Austin Nichols Nick-- Suppose the original poster wants to compare income distributions--the sd of log income is a common measure applied to such distributions, but income can be zero or negative, though mean income in some population is unlikely to be zero. The CV is a natural comparison measure, as is squared CV or any other inequality measure discussed in Stephen Jenkins' talk (http://www.stata-journal.com/article.html?article=st0095) or SSC programs (findit jenkins). ps. why not degrees Kelvin? On Fri, Jul 11, 2008 at 5:57 AM, Nick Cox <n.j.cox@durham.ac.uk> wrote: > There are some references in > > Sokal, R.R. and Rohlf, F.J. 1995. Biometry. New York: W.H. Freeman. > > The rough argument for thinking logarithmically goes like this. It makes > sense to work with the coefficient of variation whenever standard > deviation is proportional to mean. That implies that variability is > multiplicative, not additive, which in turn implies working on a > logarithmic scale. * * 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/

**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:*"Nick Cox" <n.j.cox@durham.ac.uk>

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

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