In the previous concepts, you saw how we could build confidence intervals for different parameters, like the mean or difference in means. So what are some of the scenarios for which we would want to build a confidence interval for the difference in means? Well, we could look at the effectiveness of different drugs by comparing two groups who take two different drugs, or comparing a group that takes a drug to a group that did not take a drug at all. This type of testing is common for any of the health conditions around the world. Another use case specific to learning could be to implement two different ways of teaching the same topic and see which way improves retention. One of the most common use cases for comparing two groups in this way is known as A/B testing, where we compared different webpages to one another to determine which web designs drive the largest amount of traffic. The last topic will be covered in more detail in a later lesson, as it’s the key to survival for many online companies.