 Today we're going to look at putting data in, making this category, and then looking at the actual equation on top of that data. So the first thing we want to do is go to the Y equals screen, and then we want to arrow up to plot 1, and then press Enter. This will make sure that we've turned on our plot or so that it will plot the points we want to put in. So let's put some points in. We need to hit the stat key, and then we need to edit, which is option 1, and it's already highlighted, so we press Enter. And then in here we're going to put in our data, but let's clear out what we have here. If you have data in there, like I do, just arrow up to L2 or L1, which is L1, clear, and then Enter. We'll clear it all out. And then I want to do the same thing for L1, so I arrow over, arrow up to L1, clear, and then Enter. All right, now I'm ready to put my data in. So I'm going to put in for L1, these are my X values, 0, 1, 2, 3, and 4. So 0, Enter, 1, Enter, and so forth. And then I arrow over to L2, put in my Y values, so I'm going to put in negative 2, Enter, negative 1, Enter, 0, Enter, 2, Enter, and 3, Enter. Notice I have the same number of X's as Y's, that's important, L1's and L2's. Okay, so now we have the data in there, so let's look at our graph. To do that you want to, in fact let me clear out our history here so that we can start over. Now to look at the scattergram, we want to hit Zoom, and we have all these options. And if I arrow down past what we see here, right here at 9, it says Zoom Stats. So we want to choose that. You can either press Enter here, or anytime you can just press the 9 when you're in the Zoom, and it will automatically plot our data. Now if you're following along and you don't have your data there, it's probably because you didn't turn that plot on in the Y equals screen. But now we can see that this is all the points that we just put in our data. Now we can see the graph of those points. Okay, clear our history again. And now we want to know what the equation of this line is, or the best equation. So we hit the stat key. And instead of editing this time, we want to go up here to calculate. So just arrow over to calculate, and then choose whatever kind of regression we want. That would be starting with number four. We've got linear regression, quadratic regression. But we want to use linear regression, because we can see that it's definitely a line. So we're going to choose option four. And I'm just going to press the number four. And now it asks me linear regression. And you have to press Enter to verify that's the regression you wanted. Press Enter. And then you see the equation that best fits all that data. Now let's go and put that into our Y equal screen. Now we'll just have to write this down. It's Y equal AX, and A being 1.3, plus B, and our B, that's the Y intercept, being negative 2.2. So write that down. Now I go into Y equal, and I have 1.3X, that was AX, minus 2.2, because it was negative 2.2 for the B. And now I can hit the graph key, and my line will go on top of my data. Now you can see why it's called the regression line, because not all of these points, like this one here and this one here, aren't perfectly on that line. But all of these average onto this line that we just drew.