The sample mean for y, if you just add up one plus two plus three plus six over four, four data points, this is 12 over four, which is indeed equal to three, and then the sample standard deviation for y, you would calculate the exact same way we did it for x, and you get 2.160. Now with all of that out of the way, let's think about how we calculate the correlation coefficient. Now right over here is a representation for the formula for the correlation coefficient, and at first it might seem a little intimidating. Until you realize a few things. All this is saying is, for each corresponding x and y, find the z-score for x. So we could call this z sub x for that particular x. So z sub x sub i, and we could say this is the z-score for that particular y.