Good Q WW
I suffered my way through statistics and probability theory at uni but think there's still a bit of unscarred grey matter that can assist with the answers.
Average and mean are the same; derived from the sum of the elements (ie pieces of data) divided by the number of elements. I forget why mathematicians call it the mean (rather than the avaerage), maybe it was the alliterative qualities of the word - considering it is always used in conjunction with "mode" and "median". (BTW, "conjunction" is a mathematical term also!)
The median value of a data set is the middle value (once all the elements have been put in order). This is more useful to statisticians as far flung elements at either end of the data set tend to cancel each other out. Hence you get an "unskewed" value for the median - one that is unaffected by data which may be spurious or, if not spurious, irrelevant to the data set as a whole.
The "modal value" (or "mode") of a data set is the most common value - this is handy as it is not a function of the highest or lowest value in the data set.
I proffer this in the absence of Bean - she's the guru on this stuff - with a gift for presenting the answer so that we all can understand it!
stales
