3.1 Visualising the data and assumptions of the test
We will again visualise the data to gain an overview and help us understand the data we are analysing. The below stacked bar chart can help us to understand visually how different or similar the distribution of proportions are between groups.
The assumptions we need to check for the chi-squared test of independence are exactly the same as those for the chi-squared goodness of fit test. That is:
Chi-squared test of independence assumptions:
- No more than 20% of categories have an expected count of less than 5
- There are no expected counts of zero
We will be able to check these assumptions after carrying out the test.