But with our null hypothesis, we're assuming that p1 and p2 are the same value. So let me rewrite it. So in our last video, and I don't want to confuse the issue, because in the last video I made this approximation over here. So let me write the clean version down here. We know that the standard deviation of our sampling distribution of this statistic, of the sample mean of p1 minus the sample proportion or sample mean of p2, is equal to the square root of p1 times 1 minus p1 over 1,000 plus p2 times 1 minus p2 over 1,000. We've seen this in several videos. But in the null hypothesis, we are going to assume that p1 is equal to p2.