AP Statistics 1.2 Sampling and Experimentation
AP Statistics: Sampling and Experimentation Drill 1, Problem 2. Which of the following studies would be the best approach to finding his new location?
|AP Statistics||Sampling and Experimentation|
|Statistics and Probability||Understand and evaluate random processes underlying statistical experiments|
And here are the possible answers...
Okay. We know, we know, before we even get to the real question, the more important question...
is it greek yogurt or frozen yogurt?
Let's just say it's frozen yogurt because everybody loves some froyo in town.
Back to the real question...The question asks us how Bill should measure the amount of yogurt
fanaticism by area. To do this, we'll want a survey that measures how much people like
yogurt in each of the two large cities.
Emphasis on the word SURVEY.
Since experiment E merely compares the how much people like exotic and standard yogurt by area
and is an experiment..not a survey,
we can rule out option (E) as an answer choice.
The question also mentions that we're dealing with two large cities...so doing any kind
of census where we poll every single person in the population...kind of like that government
population census they do every 10 years...
Too much money and time to do it...
Bill needs as much time as possible to perfect his new shnozberry yogurt recipe.
Therefore, we are left with three surveys: the mail-in survey, the grocery store survey,
and the phone survey, options A, C, and D.
Ok, the mail-in survey. First of all, if you
ever saw a survey in the newspaper...when have you ever actually filled it out and turned
it in? Besides...who reads newspapers anymore...
Honestly, the only people who will turn in the mail-in
survey are those feel really strongly..either positively or negatively..about establishing
a new yogurt store in the area.
Kind of like Bill.
This kind of bias is called self-selection bias.
The people being surveyed "self-select" themselves into the group that really cares
The local grocery store survey. Let's think about this. What if you just don't happen
to shop at that particular grocery store that Bill's handing out surveys?
Maybe you live too far, maybe you had a late night and couldn't get up to go with your parents to
the store...Regardless, the local grocery store surveys won't give Bill a random sample
of the city. It'll give him a sample of the people who happen to shop at the particular grocery store that day.
And finally, we're left with option D. The phone survey.
Oo, we like that word: random.
Random is usually a good indicator in stats that you're performing the right type of experiment
without sampling biases. The word stratified in this case
just means that Bill is first
dividing or stratifying the population into each of the two cities...and then choosing
random people to survey in each group. Answer's (D).
And since we like random things so much, we can't wait until Bill installs his new random
yogurt flavor-making machine. The machine will mix up to three random flavors chosen
from his exotic stock.
Watch out for the anchovy yogurt, people.