Identifying a sample and population | Study design | AP Statistics | Khan Academy

Administrators at Riverview High School surveyed a random sample of 100 of their seniors to see how they felt about the lunch offerings at the school's cafeteria.

So, you have all of the seniors; I'm assuming there's more than a hundred of them. Then they sampled a hundred of them. So, this is the sample. The population is all of the seniors at the school. That's the population: all of the seniors, and they sampled 100 of them. So, the hundred seniors that they talked to—that is the sample.

That is the sample. So, they tell us to identify the population and the sample in the setting. Let’s just see which of these choices actually match up to what I just said. Like always, I encourage you to pause the video and see if you can work through it on your own.

So, the population is all high school seniors in the world; the sample is all of the seniors at Riverview High. No, this is not right. We're not trying to figure out—we're not trying to get an indication of how all of the high school seniors in the world feel about the food at Riverview High School. We're trying to get an indication of how the seniors at Riverview High School feel about the lunch at the school's cafeteria. So, they did a sample of a hundred of them.

This is definitely not going to be right, so let me cross this one out. The population is all students at Riverview High; the sample is all of the seniors at Riverview High. Well, they clearly didn't sample all of the seniors; they sampled a hundred of the seniors. So, this isn’t going to be right either.

Let's hope that the third choice works out: the population is all seniors at Riverview High; the sample is the 100 seniors surveyed. Yep, that's exactly what we talked about here. We're trying to get an indication about how all of the seniors at Riverview High feel about the food, the lunch offerings.

We probably think it's impractical—or the administrators feel it's impractical—to talk to everyone. They’ll get exactly what the population thinks, so instead, they're going to do a random sample of a hundred of them. So, the sample is 100 seniors who are actually surveyed.