Once again on of the more essential videos of the course, for which you'll need to give your full attention. I do realize this video is rather long, so you may wish to break up your viewing into smaller segments. You will find a balanced mix of step by step examples (mostly in the last half) with attempts to add clarity and meaning to the concepts behind Hypothesis Testing. Notice also the key role played by the notion of a so-called 'P-value'. While typically very easy to mechanically 'compute', truly verbally understanding what is meant by a P=value (beyond just a memorized textbook statement) is one of the true challenges I face as the instructor of this course.