And then you could, to see if there's an association, you might take a sample, let's say you take a random sample of 20 people from the population, and in future videos, we'll talk about the conditions necessary for making appropriate inferences. Well, let's say those 20 people are these 20 data points. So there's a young child, then maybe there's a grown adult with bigger feet, and who's taller, and then three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and so you have these 20 data points, and then what you're likely to do is input them into a computer. You could do it by hand, but we have computers now to do that for us usually. And the computer could try to fit a regression line. And there's many techniques for doing it, but one typical technique is to try to overall minimize the square distance between these points and that line. And this regression line will have an equation as any line would have, and we tend to show that as saying y hat, this hat tells us that this is a regression line, is equal to the y-intercept, a, plus the slope times our x variable.