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pls answer the questions and do not use any chat gbt. My teacher is really strict and checks!!! Also my grade is borderline so make sure this is the best work! I attached the document bellow. each questions does not need to be a specific length but must fully answer the question
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Professor Julie Zissimopoulos
PPD303 Statistics for Policy, Planning and Development
Problem Set 3
Sampling
1. (10 points) In the last general election, 132,312 adults voted in Dutchess County, New
York. You plan to conduct a post-election survey of 500 of those voters. After obtaining a
list of those who voted, you number the list from 1 to 132,312. Then, you use a computer
to randomly generate 500 numbers between 1 and 132,312. Your sample consists of the
voters corresponding to the selected numbers. Determine whether the sample is based on a
simple random sampling. Give a brief explanation of your choice.
Identify which of the following types of sampling is used: random or convenience.
2. (5 points) In a clinical trial of the cholesterol drug Lipitor, subjects were partitioned into
groups which were given a placebo or Lipitor doses of 10 mg, 20 mg, 40 mg, or 80 mg.
The subjects were randomly assigned to the different treatment groups (based on data from
Pfizer, Inc.). Identify which of these types of sampling is used: random or convenience.
3. (5 points) In 1936, Literary Digest magazine mailed questionnaires to 10 million people
and obtained 2,266,566 responses. The responses indicated that Alf Landon would win the
presidential election, but Franklin D. Roosevelt actually won the election. Identify which
of these types of sampling is used: random or convenience.
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4. (20 points) Consider a study to evaluate the effect on college student grades of dorm
room Internet connections. In a large dorm, half the rooms are randomly wired for highspeed Internet connections (the treatment group), and final course grades are collected for
all residents. Which of the following pose threats to the validity of the study, and why?
(Hint: There can be multiple threats. An explanation is required for each threat.)
Note: Causality can be established when there are no other sources of bias such as
confoundedness due to lurking variables or sampling biases (voluntary
response, attrition, mortality bias, etc..).
a.
Midway through the year all the male athletes move into a fraternity and drop out
of the study (their final grades are not observed).
b. Engineering students assigned to the control group put together a local area
network so that they can share a private wireless Internet connection that they pay
for jointly.
c.
The art majors in the treatment group never learn how to access their Internet
accounts.
d. The economics majors in the treatment group provide access to their Internet
connection to those in the control group, for a fee.
5. (10 points) When it was found that hydroxyurea reduced the symptoms of sickle cell
anemia, the National Institutes of Health released a ·medical bulletin. The bulletin said,
“These findings are the results of data analyzed from the Multicenter Study of
Hydroxyurea in Sickle Cell Anemia (MSH), which was a double-blind, placebo-controlled
trial in which half of the patients received hydroxyurea and half received a placebo
capsule.” Explain to someone who knows no statistics what the terms (1) “placebocontrolled” and (2) “double-blind” mean here.
Confounding
6. (30 points) To study the effect of neighborhood on academic performance, 1000
families were given federal housing vouchers to move out of their low-income
neighborhoods. No statistically significant improvement in the academic performance of
the children in the families was found one year after the move.
a. What are the explanatory and response variables?
b. What are the subjects, factor(s), and treatment?
c. Explain clearly why the lack of improvement in academic performance after one
year does not necessarily mean that neighborhood does not affect academic
performance. In particular, identify some lurking variables whose effect on
academic performance may be confounded with the effect of the neighborhood.
d. Suppose instead that families could apply for vouchers, but that a random group of
applicants would receive them. Draw a diagram to display this study design.
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Data Ethics
Most of the exercises pose issues for discussion. There are no right or wrong answers,
but there are more and less thoughtful answers.
7. (10 points) Texas A&M, like many universities, offers free screening for HIV, the virus
that causes AIDS. An announcement regarding the screening says, “Persons who sign up
for the HIV Screening will be assigned a number so that they do not have to give their
name.” They can learn the results of the test by telephone, still without giving their name.
Does this practice offer (1) anonymity, (2) confidentiality, or (3) both? Explain.
8. (10 points) The presidential election campaign is in full swing, and the candidates have
hired polling organizations to take regular polls to find out what the voters think about the
issues. What information should the pollsters be required to give out? Please answer the
following questions:
a. What does the standard of informed consent require the pollsters to tell potential
respondents?
b. The standards accepted by polling organizations also require giving respondents the
name and address of the organization that carries out the poll. Why do you think
this is required?
c. The polling organization usually have a professional name such as “Samples
Incorporated” in order NOT to reveal to the respondents whether the poll is being
conducted by/financed by a political party or candidate. Would revealing the
sponsor to respondents bias the poll? Or should the sponsor always be announced
whenever poll results are made public?
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