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ATHK1001 Assignment 2
Due date: 11:59pm Monday, 9 May. Late penalty of 5% per calendar day applies, with a 0
mark given if more than 10 days late.
Submission: All submissions are to be made via the ATHK1001 Canvas website and they
must be in a PDF file readable by Canvas. Submissions will be checked for plagiarism.
Word limit: 1000 words in total. Answers must be complete sentences. A penalty of
10% will apply to papers that exceed this limit by more than 10%, a 20% penalty if you
exceed 20% of the limit, and 30% if you exceed the limit by 30%.
Total marks: 100 (22.5% of total for the unit)
1. “Narwhals who eat lots of halibut have longer tusks than narwhals who don’t
eat much halibut.”
1A. For 3 marks, state the three causal model types that can explain the correlation. Use X,
Y, and Z in your answer. Number them 1, 2, and 3.
1B. For 6 marks, for each of the causal models 1, 2, and 3 that you listed above, write a
complete sentence, describing the causal model using words from the quoted sentence
rather than using X’s and Y’s).
1C. For 4 marks, describe a specific third factor that might explain the correlation and how
could it explain it? (it’s ok if you already mentioned it above)
2. For each of the two possibilities for the null hypothesis (it is true or it is false),
there are two possible outcomes for a statistical test, yielding four possibilities
in total (see the first pre-recorded video of Modules:Wk 9).
List four terms for these four possibilities (4 marks)
3. To get a ticket for that festival, you must test negative on a COVID test.
3A. For 4 marks, does the sentence mean that something is necessary to get a ticket for that
festival? If so, what?
3B. For 4 marks, does the sentence imply something is sufficient to get a ticket for that
festival? If so, what?
4. Marriage Makes You Happy
The secret to happiness is assessed by a recent study. A team of researchers
analyzed data from over 300,000 people to uncover the keys to happiness across
the human life span. Interestingly, they found being married to be a stronger
predictor of happiness than whether someone was having sex regularly. “For all
measures and regions, married people had higher subjective well-being than
unmarried people,” state the researchers. “The effects were larger than for having
regular sex.”
4A For 4 marks, describe the causal model the above passage suggests in a complete
sentence using wors from the passage (no “X”s or “Y”s or “Z”s).
4B. For 4 marks, is the study likely to be an experiment or an observational study? Why?
4C. For 6 marks, using words from the passage rather than “X” and “Y”, describe an
alternative causal model that could plausibly explain the finding.
5. If you have a chit, you will get the vegetarian dinner.
The above sentence implies something about necessary and sufficient conditions for
getting the vegetarian dinner. For 4 marks, rewrite this sentence, using the words
necessary and/or sufficient in the sentence.
6. People who watch old TV shows have a higher annual death rate than people
who don’t. A website reporting on the research implies that people should stop
watching old TV shows, as that will reduce their risk of death.
6A. For 4 marks, without using jargon such as ‘X’ and ‘Y’, describe an alternative causal
model that might plausibly explain the correlation. Explain why your model is plausible.
6B. For 6 marks, invent a research study designed to test whether watching old TV shows
elevates the risk of death. Describe the measures and other variables of the study.
7. What statistical technique was described in class as sometimes useful to
separate out the effects of multiple measured variables? (2 marks)
8. If you wear a bandanna for six months, you will get brachymitris, but I’m not
going to wear a bandanna. That’s why I’m not going to get brachymitris.
8A. For 3 marks, rewrite the above as a syllogism in standard form, labelling the premises
and conclusion.
8B. For 4 marks, is the conclusion suppositionally inescapable? Why or why not?
8C. For 2 marks, is the conclusion inescapable? Why or why not?
9. Online dating profiles that mention bowling get fewer contacts from the
opposite sex than do profiles that don’t mention bowling. John Smith concludes
that a mention of bowling makes the opposite sex less interested.
For 8 marks, describe an experiment to test Smith’s conclusion.
10. Contingency tables for the truth of two propositions are described in
Modules:Wk9. Consider the following truth table:
For 4 marks, write two if-then sentences that together match the truth table.
11. One of Alex’s prerecorded videos (Modules:Wk 9) explained a comic strip
about jelly beans.
For 4 marks, in your own words, explain why we should not conclude that jelly beans cause
acne, even though the null hypothesis was rejected for one color of jelly beans.
12. Samoan vodka is not good. Because Tisnost vodka is Samoan, it’s not good.
For 3 marks, rewrite the above as a syllogism in standard form, labelling the premises and
conclusion.
13. A newspaper headline is: “Berries that prevent cancer”.
The article underneath the headline lists some berries.
For 3 marks, does the headline make a correlational or a causal claim? Explain why you
think this.
14. Many headlines from epidemiological studies, such as about nutrition, are later
contradicted by subsequent research. Why is that? (2 marks)
15. Using an optical test, a restaurant assesses the amount of bacteria on
employees’ hands when they leave work. Unfortunately, subsequent research
finds that the optical test detected bacteria in only half of the cases where the
employee truly had bacteria on their hands.
For 3 marks, write a sentence about the sensitivity or specificity of the optical test.
16. Parks have fairy-wrens when there’s bushes in the park, and that park did not
have bushes last year. There must not have been any fairy-wrens last year.
16A. For 6 marks, in 35 words or less rewrite as a syllogism, with premises and a
conclusion.
