And this is the 10% rule. If we are sampling without replacement, and sometimes it's hard to do replacement. If you're serving people who are exiting a store, for example, you can't ask them to go back into the store or it might be very awkward to ask them to go back into the store. And so the independence condition is that your sample size, so sample, let me just say n, n is less than 10% of the population size. And so let's say your population were 100,000 people. And if you surveyed 1,000 people, well, that was 1% of the population. So you'd feel pretty good that the independence condition is met.