Excellent article, but I wish the author (and numerous others) would get the terminology correct. “Positive skew occurs when the median falls below the average” should be “Positive skew occurs when the median falls below the mean”. Mean (total divided by the number of categories), median (value of the middle category) and mode (category with highest number of values) are all ‘averages’. Picky? Maybe, but for as long as I can remember politicians, by using ‘average,’ have been able to fool the populace by selectively inserting the mean or median as it suits them.
Hi Graeme, No, you're not being picky - you're right. I was waiting for and expecting someone to point it out! The first draft actually had mean written in it along with a chart of mode, median, mean on it to show graphically what skew does. Feedback was that a 700 word blog isn't the place to try and do a 101 stats course and just go with the term most people understand.