=+6.23 A medical research team wishes to evaluate two different treatments for a disease. Subjects are selected two at a time, and then one of the pair is assigned to each of the two treatments. The treatments are applied, and each is either a success (S) or a failure (F). The researchers keep track of the total number of successes for each treatment.

They plan to continue the chance experiment until the number of successes for one treatment exceeds the number of successes for the other treatment by 2. For example,