The McNemar test focuses on change from one condition or one sample response to another. In this example, the null hypothesis is that the promotion would have no effect; customers would be equally likely to change preferences from one brand to another.

- In this table, you can see that 26 customers preferred the store brand before seeing the promotion but not afterwards. This is a change in buying behavior that the manager would like not to attribute to the promotion.

- On the other hand, 48 customers said that they did not prefer the store detergent prior to the promotion but did prefer it afterwards. This is a change in the direction that would certainly please the store manager.