Comments on: Distribution of adult heights

By: Andrew Gelman

Andrew Gelman — Sat, 29 Nov 2008 19:05:39 +0000

Deb Nolan and I discuss this example in our Teaching Statistics book from 2002. We display a density curve which, as it happens, is neither bimodal nor flat on top. The distribution for men has a slightly higher variance. I agree that this is a good classroom example.

By: John

John — Wed, 26 Nov 2008 14:51:06 +0000

Thanks! I didn’t know about that article.

Like the article says, this is the canonical example of a bimodal distribution. I mentioned it in passing as an example a few days ago in a class I’m teaching. When I sat down to make some plots to take to the next class I found out I was wrong.

By: Karl Ove Hufthammer

Karl Ove Hufthammer — Wed, 26 Nov 2008 14:31:27 +0000

See also this recent paper in The American Statistician:

Is Human Height Bimodal?
Mark F. Schilling, Ann E. Watkins and William Watkins
The American Statistician, Vol. 56, No. 3 (Aug., 2002), pp. 223-229
http://www.jstor.org/stable/3087302

By: John

John — Wed, 26 Nov 2008 03:02:26 +0000

Thanks. I expected a bimodal density, so I was surprised when it came out flat on top. I suppose my expectations were backward: bimodal distributions are often mixtures, so I expected my mixture would be bimodal. With a slight change in assumptions it is bimodal, but not strongly so, still essentially flat on top.

By: Daniel Lemire

Daniel Lemire — Tue, 25 Nov 2008 23:27:41 +0000

Beautiful post. Mostly because it shows that heights does not follow a normal distribution. Ah! Ah!