What is the difference between 'precision' and 'accuracy'?

Question

What is the difference between \'accurate\' and \'precise\' ?

If there is a difference, can you give an example of

• a number that is accurate but not

Answer 1

The standard example I always heard involved a dart board:

• accurate but not precise: lots of darts scattered evenly all over the dart board
• precise but not accurate: lots of darts concentrated in one spot of the dart board, that is not the bull's eye
• both: lots of darts concentrated in the bull's eye

Accuracy is about getting the right answer. Precision is about repeatedly getting the same answer.