POLI 110-002: Investigating Politics
1Types of Claims:
(1) Read this recent editorial about housing development in Metro Vancouver from the Van-couver Sun. Then, examine the following two claims made in the article.
(i) “The land-use planning system stifles new housing supply.”
(ii) “I’d . . . suggest, in a housing affordability crisis, it’s time to exempt affordable housing from
[the land-use planning system] altogether.”
Assume you accept claim (i) is true.
(a) What type of claim is (i)? Be as specific as possible. ( 12 point)
(b) What type of claim is (ii)? Be as specific as possible. ( 12 point)
(c) If we assume (i) is true, on the basis of that alone, can we accept (ii) is true? If not, give an example of
another claim (iii) that we would have to accept (in addition to (i)) in order to accept (ii) and indicate
what kind of claim (iii) is. (1 point)
(2) Read this article about research on the efficacy of mask mandates during the pandemic
(conducted by economists at UBC). Then consider this following quote from the article:
“If the U.S. had introduced a uniform national mask mandate for employees of public-facing
businesses on April 1, the number of deaths in the U.S. would . . . have been 40 percent lower on
June 1.”
(a) What kind of claim is in this quote? (identify whether it is empirical or normative and then which
sub-type it is.) ( 12 point)
(b) Reading the article, give one example of evidence used by the study’s authors to support this claim. ( 12
point)
(c) Identify one way in which the evidence for this claim meets the criteria for scientific evidence (identify
one specific criterion it meets and explain why this is so). (1 point)
2
Concepts, Variables, and Measures
(3) Read this article about the ongoing confrontation between the Army and pro-democracy
protestors in Myanmar. Then consider the following claim:
“Violent repression of non-violent protestors by military and police forces increases support for
the protests.”
(a) Please write down a variable that corresponds to the concept “support for the protests”. (1 point)
(b) Propose a measure for the variable you gave in Q3.b (1 point)
(c) Give a hypothetical example of one way that using the variable you gave in 3(a) could lack validity
(your example does not need to be true). Be sure to explain why (in your hypothetical example) this
variable would specifically lack validity. (2 points)
(4) With a growing supply of COVID-19 vaccines, the BC CDC is thinking ahead about how
to get as many people as possible vaccinated. One obstacle to this goal is the prevalence of
conspiracy theories that COVID-19 vaccines are an excuse to implant microchips into people to
track them (see, this). You have been hired by the BCCDC to find out what fraction of people
believe this conspiracy in British Columbia, so they can decide how to allocate resources in
educating the public.
(a) Describe a measure for this variable that does not suffer from sampling bias but still produces
measurement bias. Explain clearly why the procedure would generate measurement bias. And
explain why it would not have sampling bias. (2 points)
(b) Describe a different measure for this variable that does suffer from sampling bias. Explain clearly
why the procedure would generate sampling bias. (2 points)
3
(5) The following histograms show the performance of four different measures (X1, X2, X3, X4)
of variable X. The x-axis shows the difference between the observed value of X and the true
value from each measure (XObserved −XTrue). The y axis shows how frequently differences of a
given size occur across 10,000 cases. The dark vertical line indicates where XObserved−XTrue = 0
(the measure exactly gets the right value for the variable).
X1 X2 X3 X4
−20 −10 0 10 −20 −10 0 10 −20 −10 0 10 −20 −10 0 10
0
2500
5000
7500
10000
Observed X − True X
Fr
eq
ue
nc
y
Different measures of X
(a) Which of these measures obviously suffer from systematic measurement error? (1 point)
(b) Which of these measures obviously suffer from random measurement error? (1 point)
(6) Read the following description of research currently being conducted by Statistics Canada
Statistics Canada is currently conducting the Canadian COVID-19 Antibody Health Survey. To
find out what fraction of people in Canada have contracted COVID-19 (whether symptomatic or
asymptomatic), StatsCan will contact 48,000 people living in Canada, chosen at random. People
who are contacted will complete an online questionnaire, then submit finger-prick dried blood
samples, which will be used to look for antibodies to COVID-19 that indicate a previous infection.
When the survey is completed, researchers will use the fraction of people surveyed who had
COVID-19 antibodies as an estimate of the fraction of people in Canada who have been infected
with COVID-19.
In this example:
(a) What is the population? Explain your answer. (12 point)
(b) What is the sample? Explain your answer. ( 12 point)
4
(c) What is the inference? Explain your answer. ( 12 point)
(d) In July 2020, the B.C. Centre for Disease Control (BCCDC) estimated that fewer than 0.5 per cent
of British Columbians had been exposed to COVID-19 in the pandemic’s first wave. To create this
estimate, the BCCDC randomly selected blood samples that were given for reasons other than
COVID-19 testing (e.g., to monitor medical conditions such as heart disease, diabetes, or cancer)
and tested them for the presence of COVID-19 antibodies. Give an example of one way in which the
BCCDC study might suffer from sampling bias. Explain how this example is a case of sampling
bias. (1 12 points)
(e) Would the potential sampling bias you came up with in the previous question have been solved if the
BCCDC increased the number of blood samples it examined? Explain your answer. (1 point)
(7) Identify the level of measurement for the following two variables and explain your answer.
(a) The date on which a state or province first imposed a face mask mandate (1 point)
(b) Whether or not a person has worn a face mask at any time during the past two weeks (1 point)
5