10. Name that Scenario
–
Below are a number of research problems.
For each, determine if the most
appropriate statistical analysis technique is conducting a hypothesis test (HT) or constructing a confidence
interval (CI).
Then also give the symbol for the corresponding parameter that is of interest.
[6 points]
a. Police set up an auto checkpoint at which drivers are stopped and their cards inspected for safety
problems.
They want to estimate the percentage of all cars on the road that may be unsafe.
Circle one:
HT
CI
Parameter of interest: _________________
b. A company has recently started an exercise break program for its workers to see if it will improve job
satisfaction on average, as measured by a questionnaire with higher scores indicating more satisfied.
Scores for 10 randomly selected workers before and after the implementation of the exercise program
were recorded.
Circle one:
HT
CI
Parameter of interest: _________________
c. Researcher Colinda would like to determine if the proportion of all adults favoring the death penalty is the
higher than that for all teenagers. She asks a random sample of adults (group 1) whether or not they favor
the death penalty. She also asks an independent random sample of teens (group 2) whether or not they
favor the death penalty.
Circle one:
HT
CI
Parameter of interest: _________________

11. Carbon Monoxide in LA
–
The Environmental Protection Agency (EPA) conducted a test to assess if the
population average carbon monoxide level in the downtown Los Angeles area is higher than 4.9 parts per
million (ppm).
The hypotheses tested were: H
0
:
= 4.9 versus H
a
:
> 4.9 and a 5% significance level was used. The results
from a random sample of 25 carbon monoxide readings gave a sample mean of 5.40, a sample standard
deviation of 1.03, a test statistic value of 2.43 with a corresponding
p
-value of 0.011.
Below are
possible
statements for including in the EPA report.
You have been asked to determine which
statements are appropriate to include (True) and which are not appropriate to include (False). Clearly circle
your answer for each statement. [1 point each]
a.
The value of 5% represents the tolerable risk of concluding the population

b.
The power of the test is the probability that the EPA correctly concludes

c.
The standard normal distribution was used to calculate the
p

d.
The
p
-value of 0.011 is the probability that the null hypothesis is true.
True
False

e.
Based on the data, the carbon monoxide level in all areas in downtown

12. Memory Experiment
–
A researcher conducts an experiment on human memory and recruits 10 people to
participate in her study. She performs the experiment and analyzes the results. She obtains a
p
-value of
0.13. Which of the following is a reasonable interpretation of her results? Her significance level was 10%.

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