Keep an eye on the time, however only 3 problems require a typed response and 1 requires a diagram.
Keep an eye on the time, however only 3 problems require a typed response and 1 requires a diagram.
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2 points
2
Question 1
1.
A random number generator is used to select 12 students from a large statistics class to rate a statistics video.
The 12 students selected are...
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2 points
2
Question 2
2.
The most important advantage of experiments over observational studies is that
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2 points
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Question 3
3.
What is the main purpose of the random assignment of treatments to subjects in an experiment?
The one that I said was important in our notes!
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2 points
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Question 4
4.
Two polls show significantly different results.
One asks, “Do you think school hours should be decreased?”
The other asks, “Do you think school hours should be decreased considering there is no time for outside play?”
Which of the following types of bias is/are shown by the polls?
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2 points
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Question 5
5.
A local community organizer is considering running for city council. She wants to measure her name recognition by doing a survey in the council district in which she intends to run. Which of the following survey methods would produce unbiased results?
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2 points
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Question 6
6.
A recent study of a group of 1200 teenagers, showed that teenagers who had night lights in their rooms as babies are more likely to suffer from myopia (near sightedness) than teenagers who had not used night lights.
But genetic factors are known to play a role, and near-sighted parents are more likely to install a night light in their children's room.
This makes it hard to tell if the night light caused the myopia.
This is an example of...
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2 points
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Question 7
7.
What kind of a study was #6?
Use the following information for #8 - 12.
Want to stop smoking? Nicotine patches may help, and so may taking a drug that fights depression. A report in a recent issue of the New England Journal of Medicine describes a study of what works best.
Here is part of the summary:
Use of nicotine replacement therapies and the antidepressant bupropion helps people stop smoking. We conducted a double-blind, placebo-controlled comparison of sustained-release bupropion (244 subjects), a nicotine patch (244 subjects), bupropion and a nicotine patch (245 subjects), and a placebo (160 subjects) for smoking cessation.
Results. The quitting rates at 12 months were 15.6 percent in the placebo group, as compared with 16.4 percent in the nicotine patch group, 30.3 percent in the bupropion group, and 35.5 percent in the group given bupropion and the nicotine patch.
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Question 8
8.
How many treatment groups were there?
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Question 9
9.
Which was the control group?
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Question 10
10.
One group received a placebo.
Why not just give this group no treatment at all?
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Question 11
11.
The experiment was “double-blind."
This means that...
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Question 12
12.
What additional information do we need in order to prove cause and effect of the Buproprion pill for cessation of smoking?
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2 points
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Question 13
13.
A random sample survey interviewed 3,800 U.S. adults nationwide by telephone.
One question asked was whether they agreed with this statement: "Some people say we should have a third major political party in this country in addition to the Democrats and Republicans."
In this sample, 23% of the people asked responded, “Yes, we should have a third political party.”
The population for this survey appears to be...
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2 points
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Question 14
14.
A random sample survey interviewed 3,800 U.S. adults nationwide by telephone.
One question asked was whether they agreed with this statement: "Some people say we should have a third major political party in this country in addition to the Democrats and Republicans."
In this sample, 23% of the people asked responded, “Yes, we should have a third political party.”
Can we generalize the results from the survey to all adults in the U.S.?
Select your answer and why.
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2 points
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Question 15
15.
What proportion of students are willing to report cheating by other students?
A student project put this question to an SRS of 172 undergraduates at a large university: “You witness two students cheating on a quiz. Do you go to the professor?”
Only 11% answered “Yes.”
The dotplot shows the proportion who would go to the professor in each of 1000 random samples of size 172 from a population where 11% would go to the professor.
Use the results of the simulation to calculate the approximate the margin of error for the estimate of the proportion of students who would report cheating.
Check your notes for the Margin of Error formula.
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2 points
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Question 16
16.
Use the information from #15:
Interpret the margin of error for finding the true proportion of students who would report cheating.
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3 points
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Question 17
17.
Students in a large statistics class were randomly divided into two groups of 20 each.
The first group took the midterm exam with soft music playing in the background while the second group took the exam with no music playing.
The average scores of the two groups on the exam were compared.
Create an outline(diagram of the experiment) showing how the researchers could carry out a completely randomized design for this experiment.
Create the diagram on a half sheet of paper and turn in to Mrs. Nosal, make sure your name is on it.
When you are finished, type 'Done' into the answer section.
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2 points
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Question 18
18.
Use the information in #15 & 17:
Suppose the results of the experiment showed that there was a statistically significant difference in the average scores of the two groups.
Explain what statistically significant means.
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2 points
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Question 19
19.
A researcher studied whether friendship affects the prices people set for selling things.
She had 80 students all imagine selling the same item, in this case a gently-used graphing calculator.
Half the students, assigned at random, imagined selling the calculator to a stranger.
The other half imagined selling the calculator to a friend.
Then the students were asked to set the asking price of the calculator.
On average, those selling to friends asked lower prices than those selling to strangers.
The results of this study are given in the table below:
Find the difference in mean asking price for the calculator (friend – stranger).
Make sure to use units, keep the sign if it is negative.
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2 points
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Question 20
20.
Continue #19: Two hundred trials of a simulation were performed to see if the differences in the two mean asking prices (friend – stranger) would happen only due to chance variation in random assignment, assuming that whether or not you were selling to a friend or a stranger didn't matter in determining the asking price.
Use the results of the simulation above to determine the percent of the simulations that had results equal to or more extreme than the results in #19.
Remember, look at the results that are more EXTREME than the sample (further from the mean).
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2 points
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Question 21
21.
Use the results of the simulation above in #19 & 20 to determine if the difference in mean asking prices between selling to a friend and selling to a stranger is statistically significant.
Explain your reasoning, could it have happened due to sampling variability or is it unusual.
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2 points
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Question 22
22.
The supervisors of a rural county are interested in the proportion of property owners who support the construction of a new high school for the area. Rather than contact all 7,000 of the owners, the supervisors decide to take a random sample of 300.
During each interview, the supervisor's representative asks, “Do you support the building of a new high school for the area?”
For this sample, 58% of the respondents said yes.
If the representative took a second random sample of 300 property owners, would this second sample proportion of those who support building a new high school be exactly the same as that found in the first sample?
Explain and tell what this is an example of.
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2 points
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Question 23
23.
If the representative in #22 increased the sample size to 600 owners, what effect would this have on the distribution of the estimated proportion of owners who would support building the high school?
Explain why.
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2 points
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Question 24
24.
A random sample survey interviewed 3,800 U.S. adults nationwide by telephone.
One question asked was whether they agreed with this statement:
"Some people say we should stick with two major political parties in this country, do you think we should have a third party in addition to the Democrats and Republicans."
In this sample, 23% of the people asked responded, “Yes, we should have a third political party.”
What type of bias is present in this study and how will it affect the results?
Select both answers.
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2 points
2
Question 25
25.
A random sample survey interviewed 3,800 U.S. adults nationwide by telephone.
One question asked was whether they agreed with this statement:
"Some people say we should stick with two major political parties in this country, do you think we should have a third party in addition to the Democrats and Republicans."
In this sample, 23% of the people asked responded, “Yes, we should have a third political party.”
The news article that reports the poll results says, "The margin of error is plus or minus two percentage points."
This means that...
Hint: check to see where the randomization occurs to determine to whom you can generalize the results.