But I'll write the X squared here so that it will be, and let me write it this way. This is our chi-squared statistic. But I'm going to write it with a capital X instead of a chi because this is going to have approximately a chi-squared distribution. I can't assume that it's exactly. So we're dealing with approximations right here. But it's fairly straightforward to calculate. We take, for each of the days, we take the difference between the observed and the expected.