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AP Statistics 1.2 Sampling and Experimentation 267 Views


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AP Statistics: Sampling and Experimentation Drill 1, Problem 2. Which of the following studies would be the best approach to finding his new location?

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Transcript

00:03

Here's your AP stats shmoop du jour:

00:06

Bill has decided to fulfill his lifelong dream and open an exotic yogurt store.

00:11

He has narrowed his possible future location to one of two large cities and would like to determine the

00:17

location with the most yogurt fanatics.

00:23

Which of the following studies would be the best approach to finding his new location?

00:28

And here are the possible answers...

00:35

Okay. We know, we know, before we even get to the real question, the more important question...

00:40

is it greek yogurt or frozen yogurt?

00:46

Let's just say it's frozen yogurt because everybody loves some froyo in town.

00:50

Back to the real question...The question asks us how Bill should measure the amount of yogurt

00:54

fanaticism by area. To do this, we'll want a survey that measures how much people like

00:59

yogurt in each of the two large cities.

01:05

Emphasis on the word SURVEY.

01:10

Since experiment E merely compares the how much people like exotic and standard yogurt by area

01:16

and is an experiment..not a survey,

01:22

we can rule out option (E) as an answer choice.

01:28

The question also mentions that we're dealing with two large cities...so doing any kind

01:33

of census where we poll every single person in the population...kind of like that government

01:38

population census they do every 10 years...

01:43

Too much money and time to do it...

01:45

Bill needs as much time as possible to perfect his new shnozberry yogurt recipe.

01:53

Therefore, we are left with three surveys: the mail-in survey, the grocery store survey,

01:59

and the phone survey, options A, C, and D.

02:02

Ok, the mail-in survey. First of all, if you

02:05

ever saw a survey in the newspaper...when have you ever actually filled it out and turned

02:10

it in? Besides...who reads newspapers anymore...

02:13

Honestly, the only people who will turn in the mail-in

02:15

survey are those feel really strongly..either positively or negatively..about establishing

02:21

a new yogurt store in the area.

02:27

Kind of like Bill.

02:30

This kind of bias is called self-selection bias.

02:32

The people being surveyed "self-select" themselves into the group that really cares

02:36

about froyo.

02:39

The local grocery store survey. Let's think about this. What if you just don't happen

02:44

to shop at that particular grocery store that Bill's handing out surveys?

02:50

Maybe you live too far, maybe you had a late night and couldn't get up to go with your parents to

02:54

the store...Regardless, the local grocery store surveys won't give Bill a random sample

02:59

of the city. It'll give him a sample of the people who happen to shop at the particular grocery store that day.

03:07

And finally, we're left with option D. The phone survey.

03:12

Oo, we like that word: random.

03:14

Random is usually a good indicator in stats that you're performing the right type of experiment

03:19

without sampling biases. The word stratified in this case

03:24

just means that Bill is first

03:26

dividing or stratifying the population into each of the two cities...and then choosing

03:31

random people to survey in each group. Answer's (D).

03:36

And since we like random things so much, we can't wait until Bill installs his new random

03:39

yogurt flavor-making machine. The machine will mix up to three random flavors chosen

03:44

from his exotic stock.

03:46

Watch out for the anchovy yogurt, people.

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