 Welcome to our lecture on understanding hypothesis testing. We're going to try to give you a deeper understanding of stating the null and alternate hypotheses, substantiating a claim, as well as what we're actually doing when we use sample evidence to test our hypotheses. The only way to learn statistics is just to do lots and lots of problems. And again, you'll see the methodology is always the same. It's a certain method that we use over and over again. So just keep doing problems. You'll learn this very well, and you'll understand a very important concept. And this is the basic concept you're learning in the inference part of the course. When you take a sample, there has to be some kind of margin of error, the sampling error. Just remember that. That your sample statistic, let's say the X bar, is not mule. It's an estimate of mu.