Question

A physically active lifestyle has been shown to help increase longevity. In the Wistar region of Bellaria, the average age at death is considerably higher than in any other part of the country. Wistar is the only mountainous part of Bellaria. A mountainous terrain makes even such basic activities as walking relatively strenuous; it essentially imposes a physically active lifestyle on people. Clearly, this circumstance explains the long lives of people in Wistar.
Which of the following, if true, most seriously weakens the argument?

• A. In Bellaria all medical expenses are paid by the government, so that personal income does not affect the quality of health care a person receives.
• B. The Wistar region is one of Bellaria's least populated regions.
• C. Many people who live in the Wistar region have moved there in middle age or upon retirement.
• D. The many opportunities for hiking, skiing, and other outdoor activities that Wistar's mountains offer make it a favorite destination for vacationing Bellarians.
• E. Per capita spending on recreational activities is no higher in Wistar than it is in other regions of Bellaria.

Hint:

Be critical of arguments that draw conclusions from statistical averages. Ask yourself what could be skewing the data. In this case, the demographic makeup of the population is a powerful confounding factor. An alternative cause is a classic way to weaken a causal argument.

Answer 1

The Correct Option is C

Step 1: Understanding the Causal Argument
The argument attempts to explain the high longevity in the Wistar region.
Observation: People in Wistar live longer (have a higher average age at death).
Proposed Cause: Wistar is mountainous, which forces residents into a physically active lifestyle, and physical activity is known to increase longevity.
Conclusion: The mountainous terrain is the reason for the long lives of Wistar residents.
The argument assumes that the population of Wistar is comparable to the populations in other regions in all other respects relevant to longevity.

Step 2: Analyzing the Task
We need to weaken this causal claim. The most effective way to weaken a causal argument is to provide a plausible alternative cause for the observed effect. In this case, we need an alternative reason why the average age at death in Wistar might be so high.

Step 3: Evaluating the Options
(A) This statement suggests that healthcare quality is uniform across the country. This would actually strengthen the argument by eliminating differences in healthcare as a possible alternative explanation, making the lifestyle explanation more likely.
(B) The population density (least populated) is not directly linked to longevity and does not provide an alternative cause.
(C) This option provides a strong alternative explanation. The "average age at death" is a statistic. If a region has a large influx of people who are already middle-aged or retired, this will artificially inflate the average age of the population. A population that is older on average will naturally have a higher average age at death, regardless of any local environmental factors. This phenomenon is known as a self-selection bias. People who are already older are moving to Wistar. This, rather than the mountain lifestyle making young people live to an old age, could be the reason for the high average age at death.
(D) The fact that Wistar is a vacation destination for other Bellarians is irrelevant to the longevity of the permanent residents who live there.
(E) Spending on recreation does not necessarily correlate with the level of basic physical activity (like walking) or with longevity. This information does not offer an alternative cause.
Step 4: Final Answer
Option (C) is the correct answer because it introduces a confounding variable (the migration of older people into the region) that provides a compelling alternative explanation for the statistical observation, thereby weakening the original causal claim.