A month or more ago someone off-list was confused about insulinoma.
When all else was tucked away safe and sound with further information
one aspect of confusion persisted: the person kept insisting that
Insulinoma always recurs 10 months after surgery.

Why did the person think that?

Because the term "mean" was not understood. In articles and abstracts
saying "the mean time to recurrence was 10 months" the person thought
that "mean" meant "unpleasant, miserly, small of character" so read
the statement as

"The unpleasantly small time to recurrence was 10 months."

The person took it as an absolute.

WHOOPS! In English class that would make sense, esp. when studying
writings done during the times of Victoria or Edward, but for the
article it totally alters the meaning.

In this use what "mean" actually means is "average". It is math term.
The phrase means

"The average time to recurrence was 10 months."

Mean, Mode, and Median are important terms to understand.

Say the time to recurrence for those animals who had a recurrence
during the time of the study (Notice numbers in parentheses which can
indicate the numbers of animals when those occur.) were in months:

1, 14, 9
That adds up to 24 and 24 divided by 3 is 8 so the mean would be 8
months. Why is that lower than the time frame 2 of the 3 had? Because
the 1 month one pulls it down. Alternatively, a very large one could
pull it up. Usually when mean is used there is pretty nice bell curve,
though, with the high side and low side having similar distributions,
so if the animals in the study generalize to the usual insulinoma
patients and the mean is 10 months that means you might expect as
about as many getting 8 months as get a full year.

Median is the middle value, so in the grouping above, put them in
order: 1, 9,14 and the median is 9. If the numbers had been even you
would have taken the two middle numbers and found their mean (average):

1, 9,11,14 goes to 9+11 20/2= 10 so the median then would be 10.

Mode is the most common number in the list of numbers. Notice that it
is like "mode" for "fashion" or "fad".

Mode: 1, 3, 5, 2, 6, 7, 9, 2, 10, 11, 4, 2
2 is the mode for the above list

Some resources for those who are still confused:
<http://www.manatee.k12.fl.us/sites/elementary/palmasola/mathlabtutstat1.htm>
http://math.about.com/library/weekly/aa020502a.htm
http://www.purplemath.com/modules/meanmode.htm
http://regentsprep.org/regents/Math/mean/Pmeasure.htm

Sukie (not a vet)

Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/fhc/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html

[Posted in FML 5842]