## SOLVED Describing Causal Models

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%.

This is a compulsory assessment. If you do not hand it in you will have to complete an alternative assignment for zero marks, or receive an absent fail for ATHK1001. A nonserious attempt will also receive zero marks and require an alternative assessment to be completed. A serious attempt must be written wholly by you and will have identifiable sections addressing questions representing at least 70% of the available marks.

Total marks: 100 (20% of total grade for class)

1. Before we can have in-person lectures again, we need a reliable antibody test.

For 8 marks, explain what this sentence is claiming for what is necessary and what is sufficient to have large in-person lectures again.

1. For a statistical hypothesis test, there are two possible outcomes and two possibilities for the right answer, yielding four possibilities in total.

List the four terms for these possibilities (4 marks)

1. “People who exercise are less obese, on average, than people who don’t exercise.”

3A. For 3 marks, state the three potential causal models that can explain the correlation in terms of X, Y, and Z (as spoken about in lecture videos). Number them 1, 2, and 3.

3B. For 6 marks, for each of the potential causal models, 1, 2, and 3 that you listed above, write a complete sentence, describing the causal model without jargon (no X’s or Y’s) in terms of the actual content of the sentence.

3C. 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)

1. Research Finds Jobs Makes One Happier Than Marriage

(Adapted from: https://www.forbes.com/sites/traversmark/2020/03/05/when-it-comes-to-happiness-research-finds-jobs-to-be-more-important-than-marriage/#75d583db225c). What’s the secret to happiness? It’s an age-old question — and one that is addressed in a new study. A team of researchers analyzed data from over 1.7 million people worldwide to uncover the keys to happiness across the human life span. Interestingly, they found employment to be a stronger predictor of happiness than marriage. “For all measures and regions, employed people had higher subjective well-being than unemployed people,” state the researchers. “The effects were larger than for marriage.”

4A For 4 marks, describe the causal model the above passage advocates in a complete sentence without any jargon (e.g., no “X”s or “Y”s).

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4B. For 4 marks, is the study likely to be an experiment or an observational study? Why?

4C. For 6 marks, without using jargon such as X and Y, describe an alternative causal model that could plausibly explain the finding.

1. If we get a vaccine for COVID19, everything can be fully open again.

The above sentence implies something about necessary and sufficient conditions for everything being fully open again. For 4 marks, rewrite this sentence, using the words necessary and/or sufficient in the sentence.

SOLVED Describing Causal Models

1. People who listen to very old music (like classical music) regularly have a higher annual death rate than people who don’t. A newspaper article reporting on the research implies that you should stop listening to very old music, as that will reduce your risk of death.

6A. For 4 marks, without using jargon such as X and Y, describe an alternative causal model that could plausibly explain the finding. Explain how this model is plausible.

6B. For 6 marks, describe a research study designed to test whether listening to old music elevates the risk of death.

1. Three hours in the sensory deprivation tank results in pidiacerebrosis, and I’m not going to inflict sensory deprivation on myself. That’s why I’m not going to get pidiacerebrosis.

7A. For 3 marks, rewrite the above as a syllogism in standard form, labelling the premises and conclusion.

7B. For 4 marks, is the conclusion suppositionally inescapable? Why?

7C. For 2 marks, is the conclusion inescapable? Why not?

1. An observational study finds that men who mention being members of a gun club on their online dating profiles get fewer women contacting them than men who don’t. Righteous Smith concludes that a mention of gun club membership makes women less interested.

For 8 points, describe an experiment to test Righteous’s conclusion.

1. Consider this truth contingency table:

For 4 points, write two if-then sentences that together match the truth table.

1. A lecture video discussed a comic strip (https://xkcd.com/882/) about jelly beans and acne.

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.

1. Canadian beer is not good. Because Old Guzzler beer is Canadian, it’s not good.

For 3 marks, rewrite the above as a syllogism in standard form, labelling the premises and conclusion.

1. A newspaper headline is: Superfoods to make you stronger.

The accompanying article lists a bunch of foods.

For 3 marks, does the headline make a correlational or a causal claim? Explain why you think this.

1. What statistical technique was described in class as sometimes useful to separate out the effects of different explanatory variables? (2 marks)
1. Many conclusions of epidemiological studies trumpeted by the media, for example about nutrition, later are found to be false. Why is that? (2 marks)
1. A hospital assesses the amount of virus on employees’ hands when they leave work with a new biological test. Unfortunately, more authoritative testing found that the new biological test detected the virus in only half of the cases where the employee in fact had virus on their hands.

For 3 marks, write a sentence about what you know about the new biological test, in terms of “sensitivity” or “specificity”.

1. The garden does not have snails when there’s a blue-tongued skink about, and the garden did not have snails last year. There must have been a blue-tongued skink about.

16A. For 6 marks, in 35 words or less rewrite as a syllogism, with premises and a conclusion.

16B. For 3 marks, is the the garden argument suppositionally inescapable? Explain your answer.

Total = 100 possible marks.

SOLVED Describing Causal Models

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