Wednesday, February 27, 2013

Median Versus Average

Median is not average. In fact, given typical power law distributions such as long tails the median is often lower than average.

Given a set of one mile race times: 4:14, 4:35, 4:41, 4:44, 4:49, 4:53, 4:58

The average is the sum of those times. If they are added together you get 1974 seconds. The average is 4:42.

The median is the middle time. The guy who has 50% ahead of him and 50% behind him. In this case that is 4:44.

In other words, being the "average" or "above average" at something, like running, income or drinking alcohol, often means much more than the median.

2 comments:

  1. Oftentimes you insult the intelligence of your readers ...

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  2. Perhaps, but at least one seven year old has read my blog. Plus a number of college kids that aren't science and engineering majors read it from time to time.

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