I have told this story quite a few times, but at the moment I seem to feel like I ought to get it down once and for all. Back when I were a lad I went to Wolstanton Grammar School in Wolstanton, Staffordshire. It was a rough, hard and daunting school. I can honestly say that I pretty much hated every minute of it from 1972 until 1978. I did my O Levels in 1978 and I did alright, I stayed on to do A Levels until 1980 and again I did enough to get me to university. I actually really did enjoy doing A Levels, it was all a bit different once you could concentrate on three subjects that you cared about. University was a ticket out of Staffordshire, as much as I love the place, I couldn’t see myself being there forever. One thing I really did love about my school was studying Physics and our amazing Physics teacher Mr Stanway. On the very last day of ‘compulsory school’ in 1978, Stanway was on full form and the lesson went like this:
Stanway: OK lads its the last day of term so we are going to have a test!
Pupils: Oh sir! That’s so unfair everyone else is messing about and we have to do a test!!!
Stanway: It is a test, but is going to be an interesting test, first question: ‘How many hairs are there on Mr Quincy’s head?’
Pupils: He’s bald – he has no hair!
This wasn’t strictly true, he had some hair but just a grey rim where there was some hair. So the idea was to work out how many hairs grew in each square centimeter of skin: Guess? about 20, possibly 50, so let’s say 30 (this is the guess). Now looking at Quincy’s head there is probably an area of about 3cmx25cm=75 square centimeters (this is the calculation) where there is hair, so 75×30=2,250 hairs! This is definitely not zero like some people my think, but at the same time it is not 50,000. This is true guesstimation, a guess and a calculation. Next Question….
Stanway: ‘How many blades of grass on the football pitch?’
Pupils: Oh god…..
But you can see the point, guesstimation is a combination of a guess and a calculation. Even though the answer might not be totally correct, it will be usually within the right magnitude, so when we guess 2,250 hairs on Mr Quicey’s head it might be 2000, but we know it is not going to be 200 and not 20,000. This guesstimation technique allows us to make useful calculations and avoids wild guesses and unproven, made up statistics.
Mr Stanway was a brilliant teacher, he taught me about particle accelerators, anti-matter and all sorts of wonderful things. One day, just for a laugh, we worked out Einstein’s Relativity from scratch. The end bit where you cancel out all the t (=time) and are left with E=mc² is just brilliant. When I think of some other Stanway stories I will write them here, but for now, do try to guesstimate, don’t just guess and don’t make up statistics – there is far too much of that going on these days.