Accurate or precise?

The question of accuracy or precision often confuses people — even some pharmacists.

Accuracy is usually defined as the extent to which a measurement represents the true value of that which is being measured.

Precision is more esoteric, and refers to the reproducibility of the result. If a pipette always delivers exactly 48ml ± 0.1ml of water when we measure out 50ml, it is precise to 0.1ml, or 0.2 per cent, but is not particularly accurate, being 2ml out.

When Merlin debated with undergraduate students the difference between accuracy and precision, he always said that his watch showed the time with a precision of one second, but if it was about 10 minutes fast it was not accurate!

Likewise, how to distinguish between knowledge and wisdom? This problem has engaged philosophers, theologians and others for centuries. Merlin has a ready rule of thumb.

Botanically speaking, a tomato is a fruit. This is knowledge. However, not serving them with custard requires wisdom.