So one way to think about it, our total variation was 30. And based on this calculation, 6 of that 30 comes from variation within these samples. Now the next thing I want to think about is, how many degrees of freedom do we have in this calculation? How many kind of independent data points do we actually have? Well, for each of these, so over here, if you know, we have n data points in each one. In particular, n is 3 here. But if you know n minus 1 of them, you can always figure out the nth one if you know the actual sample mean.