Who's the greatest sports person of all time?
Clearly, whoever it is has to also be the best in the history of their particular sport. But there are lots of sports, and equally many best players. Who's better - the greatest footballer, or the greatest golfer, or...?
You could just pick your personal favourite. If you like soccer, then Pelé is probably the greatest sportsman. Those who prefer baseball would most likely plump for Ty Cobb. But is there a way of objectively deciding who's the greatest of the great?
Yes, and the answer is Australian cricketer Sir Don Bradman (1908-2001). Why? It's all down to ?, the standard deviation - a fantastically useful, yet often misunderstood, mathematical technique. Time for a quick stats lesson.
For any collection of numbers, it's easy to calculate the mean - the sum of the numbers divided by how many there are. For example, ...
