In the last video, we were able to find the equation for the regression line for these four data points. What I want to do in this video is figure out the r squared for these data points. Figure out how good this line fits the data, or even better, figure out the percentage, which is really the same thing, of the variation of these data points, especially the variation in y, that can be explained by a variation in x. So to do that, I'm actually going to get a spreadsheet out. I actually have tried to do this with a calculator, and it's much harder. So hopefully this doesn't confuse you too much to use a spreadsheet. And I'm going to make a couple of columns here.