And that was M times N minus 1. Now let's just think about what this is doing right here. If this number, if the numerator is much larger than the denominator, then what that tells us is that the variation in this data is due mostly to the differences between the actual means, and is due less to the actual variation within the means. That's if this numerator is much bigger than this denominator over here. So that would make us believe, that should make us believe, that there is a difference in the true population mean. So if this number is really big, it should tell us that there's a lower probability that our null hypothesis is correct. If this number is really small, let's say that this is larger, let's say that our denominator is larger, that means that our variation within each sample makes up more of the total variation than our variation between the samples.