This section focuses on the distinction between binary and binomial data.

For binary regression, all the data in our outcome variable has to be a 0 or a 1. For example, the correct variable below:

participant question correct
1 1 1
1 2 0
1 3 1
... ... ...

But we can re-express this information in a different way, when we know the total number of questions asked:

participant questions_correct questions_incorrect
1 2 1
2 1 2
3 3 0
... ... ...

To model data when it is in this form, we can express our outcome as cbind(questions_correct, questions_incorrect)