If you know this one and this one, you can figure out that one. If you know that one and that one, you can figure out that one. And that's because this is the mean of these means over here. So in general, if you have m groups or if you have m means, there are m minus 1 degrees of freedom here. So there's m minus 1 degrees of freedom here. Let me write that. There are m minus 1 degrees of freedom.