And so let's think about this. How much of the total variation in y, there's obviously variation in y. This y value is over here, this point's y value is over here. There's clearly a bunch of variation in the y, but how much of that is essentially described by the variation in x or described by the line? So let's think about that. First, let's think about what the total variation is. How much of the, we could even say total variation, how much of the total variation in y?