**What is McNemar’s Test?**

The McNemar Chi-Square test is used in situations * where data is not independent*.

Specifically data is either **matched** (e.g. 2 people matched on similar characteristics, typically have different exposure – outcomes compared) or **before-after** data (e.g. one person measured before and after exposure – outcomes compared)

- It is a non-parametric test
- Tests the difference between paired proportions
- Uses RAW numbers

**Formulae… How to calculate McNemar’s test**

- Data should be placed into a trusty 2×2 table
- As this is paired data, we will be ignoring concordant cells (a and d)
- Plug b + c numbers into the formulae above… et voila!

As with the Chi-Square test, the cut-off point for 95% significance level is 3.85 (which is 1.96 squared). Therefore if the result is bigger than 3.85, we can say it is statistically significant at the 95% level (where p=0.05)

**Here is a handy flow-chart to help decided which test to use.**

…This was ‘borrowed’ from this useful website on commonly used statistical tests