Median is the Message
Today's Guardian has an article about the rise in the average cost of a wedding. What the authors of this kind of article never seem to remember (or know in the first place) is that the distribution of this sort of thing is highly positively skewed.
If 999 people spend £1002 pounds on their wedding, and Posh and Becks (say) spend £1,000,000, then the average wedding costs £2000. Of course, no one has spent £2000 on their wedding, and the vast majority have spent much less.
Similarly, they say the "average" guest spends £300, but I've never spent anything approaching that on a wedding - the median should be the message, because the median represents the amount of money that half of people spend above, and half spend below.
If 999 people spend £1002 pounds on their wedding, and Posh and Becks (say) spend £1,000,000, then the average wedding costs £2000. Of course, no one has spent £2000 on their wedding, and the vast majority have spent much less.
Similarly, they say the "average" guest spends £300, but I've never spent anything approaching that on a wedding - the median should be the message, because the median represents the amount of money that half of people spend above, and half spend below.
2 Comments:
I couldn't agree more with the sentiment of this post... people feel at ease with the mean but this needs to change and the media needs to educate their readers on the differences. But lets face it the median does NOT sell news papers!!
That's true. There is a nice example of this in the book The Dilbert Principle, by Scott Adams. , where he says (something like), journalists can work hard, find out the facts, get to the bottom of a story and then explain it clearly to their readers. Or they can write what someone tells them to. Both these jobs pay the same.
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