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Difficulty: Very hardSampling and Survey Flaws

City Planner: Critics argue that converting downtown commercial streets into pedestrian-only zones harms local retail economies by restricting vehicular access. However, a comprehensive review of pedestrian-only zones established nationwide over the last two decades demonstrates otherwise. Researchers analyzed the financial trajectories of the retail businesses currently operating within these zones. After controlling for regional economic trends and inflation, the data shows that these businesses experienced, on average, a 30 percent increase in both their profit margins and absolute net profits following the transition. Clearly, pedestrianizing commercial streets profoundly enhances retail profitability.

Which one of the following most accurately describes a flaw in the city planner's reasoning?

  1. A
    It takes for granted that a substantial increase in the proportion of profit guarantees an equivalent increase in the absolute number of sales transactions.
  2. B
    It ignores the possibility that the observed increase in net profits was caused by broad regional economic improvements rather than the pedestrianization policy.
  3. It bases a generalization about the economic impact of a policy on a sample that systematically omits entities that failed to survive that policy.Answer
  4. D
    It relies on an illicit shift in the definition of the term 'profitability' between the premise outlining the researchers' data and the final conclusion.
  5. E
    It inappropriately infers that a policy will benefit all commercial retail sectors merely because it has been shown to benefit a certain proportion of the businesses studied.

Answer

The argument bases a generalization about the economic impact of a policy on a sample that systematically omits entities that failed to survive that policy.
The correct answer accurately identifies a severe sampling flaw known as survivorship bias. By restricting the economic review exclusively to businesses 'currently operating' in the pedestrian zones, the researchers systematically excluded any businesses that suffered financial ruin and closed due to the policy change. Thus, the sample is inherently biased and cannot logically support a general conclusion about the policy's overall impact on retail profitability.

Step-by-Step Solution

1
Analyze the city planner's conclusion.
The conclusion is that pedestrianizing commercial streets profoundly enhances retail profitability.
Identifying the main conclusion is the required first step in evaluating any logical argument's structure.
2
Examine the premises supporting the conclusion.
The evidence relies on a review of retail businesses 'currently operating' within pedestrian-only zones, which show a 30 percent increase in profit margins and absolute net profits after controlling for regional trends.
Understanding the precise evidence and the parameters of the study reveals the structural limits of the argument.
3
Identify vulnerabilities or gaps between the premises and the conclusion.
The study exclusively evaluated businesses that are 'currently operating.' It excluded any businesses that went bankrupt, closed, or relocated immediately following the pedestrianization. This introduces a severe survivorship bias.
In sampling flawed arguments, the data subset usually excludes a critical demographic that would actively undermine the conclusion.
4
Select the option that accurately describes this specific sampling flaw.
The correct option identifies that the generalization is based on a sample omitting entities that failed to survive the policy change.
This abstract phrasing precisely matches the identified survivorship bias within the stimulus.

Key Concept

Sampling and Survey Flaws (Survivorship Bias)
Estimated Time:2m 0s
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Topics

Sampling and Survey Flaws

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