average

Formally, "average" refers to one of two measures of a data set: The data set's mean: sum all the items in the data set and divide by the number of items summed. If three children have heights of 2 feet, 3 feet, and 5 feet, then their mean height is 3 and 1/3 feet. Imagine an extra-long yardstick. Now let's say we hang bowling balls of equal weight from the yardstick at the 2-foot mark, the 3-foot mark, and the 5-foot mark. Assuming the bowling balls don't all slide off, the yardstick should balance if it's held near the 3 and 1/3 foot mark. This is a general observation about the mean that might be helpful if you're wondering what to think of it. The data set's median, or its middle item. If three children have heights of 2 feet, 3 feet, and 5 feet, then their median height is 3 feet. Statisticians disagree on how the median is defined with respect to a data set with an even number of elements. It's really quite unfortunate the way "average" has come to mean two things. I strongly recommend the use of "mean" or "median" if you know what the fuck you're talking about. Informally, the word "average" is even more misused. I can accept sentences like "The average adult watches 4.5 hours of television a day," even though they're technically incorrect--a little rhetorical flourish is fine. But the commonly accepted meaning of "average" is certainly **not** "just under par", as some Urban Dictionary users seem to use it.