Week 10 Quiz

Which description fits a correlation, as the course uses the term?

Select one.

• A pattern in which two things tend to go together, which by itself does not show that either one causes the other
• A claim that one thing makes another happen, backed by a pattern that shows up again and again over time
• A third factor that drives two other things at once, so that they rise and fall together without causing each other
• A pattern between two things that shows up only by chance, most often when it rests on a handful of cases

In the hot-weather table (illustrative), 28 of the 50 high-ice-cream-sales days had many sunburn cases at a beach clinic. What percent of the high-sales days had many sunburn cases?

Select one.

• 28 percent
• 56 percent
• 32 percent
• 44 percent

In the hot-weather table (illustrative), high-sales days had many sunburn cases more often than low-sales days overall. Within hot days the two shares are 80 percent and 80 percent, and within mild days they are 20 percent and 20 percent. What does the table show?

Select one.

• Ice cream causes sunburn, since the overall shares differ between the high-sales days and the low-sales days
• Sunburn makes people buy ice cream, since the causal arrow runs from the clinic visits back to the sales
• Nothing at all, since a table that gives two different answers must contain an error in its counts
• Hot weather is a confounding factor behind both, since the gap disappears once temperature is held fixed

A classmate says the hot-weather table (illustrative) must contain a counting mistake, since its overall shares seem to blame ice cream. Which reply is accurate?

Select one.

• The classmate is right, because a confounding factor is a kind of error in how the data were recorded
• The classmate is right, because the overall shares and the within-temperature shares cannot all be correct
• Every count is accurate; the flaw is reading a cause from groups of days that differ in temperature
• Every count is accurate, and the overall shares show that ice cream causes sunburn after all

In the hot-weather table (illustrative), 10 hot days had low ice-cream sales, and 8 of them had many sunburn cases. What percent of those low-sales hot days had many sunburn cases?

Select one.

• 8 percent
• 80 percent
• 20 percent
• 10 percent

Scenario (illustrative): people who use a fitness app are fitter than people who do not, but people who are already fit may be the ones who download a workout app. Which rival to the causal reading does this describe?

Select one.

• Reverse causation, the causal arrow running the other way from the one claimed
• A confounding factor, a third factor that drives both the app use and the fitness
• Coincidence, a pattern that shows up by chance because it rests on a few cases
• After this, therefore because of this (post hoc), a cause inferred from order alone

A tutoring center (illustrative) finds that students who chose its evening review sessions did better, but the most motivated students may be the ones who chose them. Which change would best let the center trace a difference in grades to the sessions themselves?

Select one.

• Compare far more students who chose the sessions with far more who did not, so the groups are larger
• Ask the students who attended whether they felt the sessions helped them earn better grades
• Count how many sessions each attending student went to and compare that with the grades they earned
• Use a lottery to decide which students attend, so that motivation and other factors split evenly

Passage (illustrative): "I wore my lucky socks to the exam and passed, so the socks helped me pass." Which fallacy does the passage commit?

Select one.

• Hasty generalization, because it rests on what happened at one exam
• Unsupported slippery slope, because it predicts a chain of passing grades
• After this, therefore because of this (post hoc)
• Attack on the person (ad hominem), because it is about the student who passed

Passage A (illustrative): "If we let students bring coffee into the library, next they'll bring full meals, then grills, and soon the building will burn down." Passage B (illustrative): cutting the late-night bus route leaves late-shift workers without a ride, so some drive instead and late-night traffic rises, with each step backed by the city's own ridership counts. Which verdict fits?

Select one.

• Both are unsupported slippery slopes, because both predict bad consequences from a single first step
• Passage A is an unsupported slippery slope, while Passage B is reasonable because each of its links is backed
• Passage B is an unsupported slippery slope, while Passage A is reasonable because each of its steps is likely
• Neither is a slippery slope at all, because neither one says that the first step guarantees the final outcome

Scenario (illustrative): two plants of the same kind sit in the same soil and are watered on the same days. One sits on the kitchen windowsill and stays green; the other sits above a heating vent and wilts. Which of the methods from Mill (1843), A System of Logic, does this comparison use?

Select one.

• The method of difference, which compares a case with the effect and an otherwise alike case without it
• The method of agreement, which finds the one factor shared by every case of the effect
• The method of residues, which subtracts the parts of an effect that known causes already explain
• The method of concomitant variation, which links two things that rise and fall in step together