And from that sample, maybe we calculate a sample proportion. And then using this sample proportion, we calculate a confidence interval on either side of that sample proportion. And what we know is that if we do this many, many, many times, every time we do it, we are very likely to have a different sample proportion. So that'd be sample proportion one, sample proportion two. And every time we do it, we might get, maybe this is sample proportion two. Not only will we get a different, I guess you could say center of our interval, but the margin of error might change because we are using the sample proportion to calculate it. But the first assumption that has to be true and even to make any claims about this confidence interval with confidence is that your sample is random, so that you have a random sample.