----- Forwarded message from Ronny Richardson -----
Several references I have looked at define skewness as follows:
mean > median: positive, or right-skewness
mean = median: symmetry, or zero-skewness
mean < median: negative, or left-skewness
----- End of forwarded message from Ronny Richardson -----
At best it is a rule of thumb, not a definition. The definitions in
terms of moments are attempts to give precise meaning to intuitive
ideas. They are not entirely successful, with success decreasing
rapidly with the order of the moment.
Statistics textbooks tend to be almost universally sloppy about
distinguishing between what is a mathematical theorem and what is a
rule of thumb. And when discussing theorems, they very often omit the
hypotheses under which the theorem is true, i.e., they state a rule of
thumb, not the theorem (which is a conditional statement).
_
| | Robert W. Hayden
| | Work: Department of Mathematics
/ | Plymouth State College MSC#29
| | Plymouth, New Hampshire 03264 USA
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