Lit cigarette

Smoking gun

Understanding the stats

Q: My mum doesn’t like that I smoke, but I don’t think it’s a big deal. My great-grandma has smoked since she was 15 and is still going at 90!

A: A common misconception is that your own experience – or those of your friends or relatives – can be generalised to everyone else. As a famous quote by English statistician and biologist R A Fisher says, “That is an experience, not an experiment.” Just because your great-grandma has survived to that age doesn’t mean you will; you can’t get meaningful data from a sample size of one. This is why most scientists use experiments that collect large volumes of data, rather than relying on anecdotal case studies.

Lead image:


Further reading

About this resource

This resource was first published in ‘Number Crunching’ in June 2013.

Statistics and maths, Health, infection and disease
Number Crunching
Education levels:
16–19, Continuing professional development