 Today, we're going to look at making a scattergram and looking at putting data in, making a scattergram 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 one and then press enter. This will make sure that we've turned on our plotter 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 one 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. Alright 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. 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 stat. 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 graphed or 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. Eventually we'll be able to look at exponential regression. Those are the main ones that we do in 110. 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. Notice we'll 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's 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.