# analysis

## Maths of coincidence

In What are the chances? we saw how the chance of a rare event occurring could be calculated for specific problems.

## Why coincidences happen

When we experience a surprising event and wonder about the likelihood of such a coincidence, we may be able to use probability theory to work out the chance of it happening. And whether the coincidence happens to us or to someone else, we need to take into account how many opportunities there are for it to happen.

## Refining Lottery Tests

National Lottery Level 3 showed how the standard $\chi^2$ goodness-of-fit statistic could be adjusted to allow for non-independence induced by the need to have exactly six unique numbers appear at each draw.