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Video transcript

city councilwoman kelly wants to know how the residents of her district feel about a proposed school redistricting plan which of the following survey methods will allow Councilwoman Kelly to make a valid conclusion about how residents of her district feel about the proposed plan so before we even look at these we have to realize that if you're trying to make a valid conclusion about how the residents of her entire district feel about the proposed plan she has to find a representative sample or not kind of a skewed sample that would just sample parts of her district so let's look at her choices should she just ask her neighbors well her neighbor she might live in a part of the neighborhood that might unusually benefit from the redistricting plan or might get hurt from the redistricting plan and so just her neighbors wouldn't be representative of the district as a whole so just asking her neighbors probably does not make sense ask the residents of Whispering Pines retirement community so once again this is not the first ones cused by geography she's she's over sampling her neighbors and not the entire district here she's over sampling a specific age demographic so he or she is she's over sampling ret older residents who might have very different opinions than middle aged or younger residents so that doesn't make sense either ask 200 residents of her district whose names are chosen at random well that seems reasonable it doesn't seem like you know there's some chance that you somehow oversample one direction or another but it's most likely to give a reasonably representative sample this is a pretty large sample size so it's important to say what is the random process where is she getting these names from but this actually does seem reasonable ask a group of parents at the local playground well once again this is just like asking asking your neighbors and it's also sampling a specific demographic now this might be the demographic that cares most about the schools but that she wants to know how her whole district feels about the redistricting plan and once ago this is at a local playground this isn't that you know all the playgrounds in the district somehow so I wouldn't do this one either let's do one more of these Mimi wants to conduct a survey of her 300 classmates to determine which candidate for class president Napoleon Dynamite or Blair Worrell Waldorf is in the lead of the upcoming election Mimi will ask the question if the election were today which candidate would get your vote which of the following methods of surveying her classmates will allow me me to make valid conclusions about which candidate is in the lead so let's see ask all of the students at Blair's lunch table no that would skew it in Blair's favor probably that's not a representative sample ask all the members of Napoleon's soccer team no same thing they're likely to go to poll Ian's way or maybe they don't like Napoleon maybe they'll go against Napoleon but either way this seems like a skewed sample put the names of all the students in a hat and draw 50 names ask those students whose names are drawn well this seems like a nice random sample that could be nicely representative of the entire population ask all students whose names begin with N or B well this could be perceived as kind of random but notice n is the same starting letter as Napoleon B is the same starting letterblair you might say well that's fair you're doing it for each of their letters but maybe there's like 10 people whose name start with an N and only two people whose names start with a B once again you're not even getting a large sample and then on top of that maybe there's some type of people with the same starting letter somehow like each other more so I would I would steer clear of this one ask every student in the class well that would work you know there's 300 classmates that might not be that time-consuming and that would be pretty good you can't get a better sample than asking everyone in the population which of the following methods of surveying your classmates will allow me me to make a valid conclusion about which candidate is in the lead well that's a pretty good conclusion people might change their mind so it's not a done deal but that's you can't get a better sample size than the entire population assign numbers to each student each students each student in the class and use a computer program to generate 50 random numbers between 1 and 300 ask those students whose numbers are selected well this is pretty close to put the names of all the students in a hat and draw 50 names so I would give this one that seems reasonable as well