A/B/n testing
One of the most common exploration strategies is what is called A/B testing, which is a method to determine which one of the two alternatives (of online products, pages, ads etc.) performs better. In this type of testing, the users are randomly split into two groups to try different alternatives. At the end of the testing period, the results are compared to choose the best alternative, which is then used in production for the rest of the problem horizon. In our case, we have more than two ad versions. So, we will implement what is called A/B/n testing.
We will use A/B/n testing as our baseline strategy for the comparison with the more advanced methods that we will introduce afterwards. Before going into the implementation, we need to define some notation that we will use throughout the chapter.
Notation
Throughout the implementations of various algorithms, we will need to keep track of some quantities related to a particular action (ad chosen for display) ....