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]