16 May 2014

Coded Averages

Teaching coding in Statistics 1 is a bit of a pain.  My pupils just don't like it, and it's hard for me to get enthusiastic about something that didn't really exist when I studied Statistics (perhaps because it's not entirely necessary?). When I was revising this topic with my Year 12s this year, I used a really simple real-life example:

Imagine I'm queuing up to buy four items of clothing, which cost £29.95, £49.95, £59.95 and £99.95. To pass time I decide to work out the mean price of these 4 items. To make the numbers easier to deal with, I add 5p to each amount and then divide by 10, giving me £3, £5, £6 and £10. It's very easy to work out the mean of these 'coded' prices in my head - it's £6. And now I can uncode that mean by multiplying by 10 then subtracting 5p (the inverse of the original coding).  That quickly gives me the actual mean price of the clothes, which is £59.95.  

Here's a few resources I've found for teaching this topic:
There's a limited selection here so perhaps I should write something myself - I'll add it to my list!

1 comment:

  1. Hi Jo, the schoolworkout.co.uk link appears to be broken