 This bootcamp takes you through several mathematical concepts and techniques that you need in order to do the introduction to statistics course. Okay, what does a straight line mean? In this example, we see our study that's x and y is the grade on a certain quiz. This actually turns out to be a straight line. In a moment, you'll see how we know it's a straight line, but we plot it for you on the right, and you see these five points are exactly on a straight line. Once we know something's a straight line, we can answer questions like, you know, what would y be the grade if x, our study, is 6? What would the grade be if you study 0 hours? That's why we want to be able to plot a straight line. And of course, we need to know what is the equation of the straight line. A straight line is defined by a slope, that's a change in y of a change in x. It shows you how much y changes as x changes. In the previous problem, the grade, the y, changed by 10 points every time hours studied x changed by 1. So we say the slope is plus 10. Again, it's the change in y, which is the change in the grade, over change in x, change in hours studied. Now, the A, that's called the intercept, the y-intercept. That's the value of y when x is 0. If you didn't study at all 0 hours, what do we predict your grade would be? In this problem, we see it would be 25. So now we can actually write out the equation. Y, and notice that little symbol on top of it, the hat, y hat equals 25 plus 10x. Every straight line is defined by an intercept term and by a slope. Why do we use the symbol y hat? Because we don't want to confuse it with the y, which is your original data points, your actual data points. In order not to confuse it, you don't know that y hat is the actual line. So we say y hat equals 25 plus 10x. Here's a second example, just to give you some more exercise. We have x and y, we're not even giving you a story about it. I don't know what x is and what y is. But notice here, the numbers are going in the other direction. They're going down instead of going up the way the numbers in the first example are going. Let's see what happens. We see that as x increases by 1 each time, y decreases by 5. So the slope is negative 5. This is an inverse relationship between x and y. And obviously when x is 0, the y intercept would be 50 if we extend it. And the equation ends up being y hat is equal to 50 minus 5x. To find more boot camp modules, visit the stat course at the URL you see there. And go to the navigation bar on the left, click boot camp. And you'll see all kinds of things that are good to do prior to the statistics course. Many of you have already done this before and maybe only need a refresher.