 already abstracted quite a bit from the experiment. We ignore whether Paul went left or right first, how long it took him to open the first container, … These are all aspects of Paul’s behaviour which we could have focused on, and hence could be variables in our data. These variables have different characteristics. For instance, accuracy (correct or incorrect) and direction (left or right container) both have only two possible values, while the duration until opening the first container has many possib