Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Re: st: How do I test that two subsample have different coefficient of variation?


From   "Austin Nichols" <austinnichols@gmail.com>
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 12:12:03 -0400

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/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index