October 2001 
Vol. 3, No. 10 


Quality Quiz
from Dr. Cleary
Congratulations! 

The coefficient of variation is a measure of how
much variation exists in relation to the mean
The standard deviation alone is sometimes not particularly useful, without a
context within which one can determine meaning. For example, knowing that the
standard deviation is 1.76 has no meaning; but understanding that a standard
deviation of 2 had been anticipated gives a context that recognizes that
variability is less than expected. Knowing that the standard deviation has
historically been .5 or less for a particular dimension, on the other hand, 1.76
would be considered high. Without perspective, the figure for standard deviation
has limited meaning.
If the number is large, the data has a great deal of variability with respect to the mean.
If the number is smaller, this reflects a small amount of variability relative to the mean.

Copyright 2001 PQ Systems.
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