Use and abuse of Statistics I

[graeme]

After the relative success of my previous puzzles, here's some more statistical "facts".
They are all wrong in some way (which varies according to the "fact"). Most of them are true but in a misleading way.
The object of the puzzle is to explain what's wrong with these "facts" and (if you can) give a better explanation of the statistic.
You may recognise some of them from attention gathering headlines.
They are listed in rough order of difficulty - I'll post them in two lots for ease of discussion.


1) Firemen cause fires!

2) Taller people have shorter hair

3) Taller people are more intelligent

(does this man that intelligent people have short hair? Hmmm, may be)

4) There are more 65 year olds than 64 year olds.

[graeme]

I've posted the answers, with brief explanations in

Use and abuse of Statistics II

Graeme