Dear All
Some books say that the coefficient of variation can only be used if the random variable is positive. I would like to know why cannot one extend the use of the same coefficient with not necessarily positive random variables but with positive mean. Could somebody here please help me?
some on various lists have claimed that the coefficient of variation ... which is usually expressed as a % of the following ratio: SD / mean ... is a useful tool
i have NEVER been convinced that this is so
while the SD can't be - ... the mean could be ... so, there is nothing conceptually against the notion of a - COV ...
what you make of it is entirely a different matter ...
let's say we have SAT scores where the mean is about 500 and the SD about 100 ... here ... the COV is 100/500 = 20%
compared to another case where the data are temperatures ... where the SD = 5 (and it's not even this in honolulu!) and the mean is 80 ... so the COV = 5/80 = 6%
for the life of me, i have never seen how this comparison of 20% versus 6% has ANY useful meaning
does anyone out there?
Thank you a lot in advance!
Paul . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
---------------------------------------------------------- Dennis Roberts Email: [EMAIL PROTECTED] Web: http://www.personal.psu.edu/users/d/m/dmr/droberts.htm
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