Re: Comparing two variation coefficients


Alfred wrote:
Thanks,

Here is a practical situation where it can be useful
to test for difference between two CV :

CV (also named "Relative Standard Deviation") is a recognized measure of
measurement repetability in Analytics. For instance, in can be used to
monitor drug tablet homogeneity (the so called "uniformity content test"
is a pre-requisite of the FDA for approval).

see : http://www.fda.gov/ora/compliance_ref/cpg/cpgdrg/cpg460-600.html

While it is true that the FDA used the term "relative standard
deviation",
but there is no indication that it meant CV!

Surely the statisticians in the FDA are not THAT statistically
challenged.
Or are they?

Is the FDA ignorant of the term Coefficient of Variation? If so, why
does it
use the ill-defined and undefined term "relative standard deviation"
repeatedly in the document? In particular it never even suggested
WHAT
the standards were.

So, how can you test if something meets the FDA standard if you don't
even know what the FDA is talking about?

-- Bob.

.