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Difficulty: HardSampling and Survey Flaws

A multinational corporation recently introduced a voluntary wellness program for its employees. After one year, an independent consulting firm evaluated the program's effectiveness by surveying employees who had actively participated in the program for at least six months. Over 85 percent of the surveyed employees reported significant improvements in their physical health and a reduction in workplace stress. Based on these results, the consulting firm concluded that the wellness program is highly effective at improving employee well-being and should be implemented across all branches of the corporation.

Which one of the following is the most serious flaw in the consulting firm's argument?

  1. It draws a broad conclusion about the efficacy of a program based on a sample of individuals whose continued participation makes them unrepresentative of the target population.Answer
  2. B
    It inappropriately infers that the program will be effective for all employees from evidence that it was effective for most of the employees in the survey.
  3. C
    It takes for granted that the reported improvements in physical health were actually caused by the wellness program rather than by some other coincidental factor.
  4. D
    It assumes that what is true of a specific, localized subset of employees must also be true of the corporation's workforce as a whole.
  5. E
    It draws a conclusion about absolute numbers of employees benefiting from the program based solely on evidence regarding percentages.

Answer

The option stating that it draws a broad conclusion based on a sample of individuals whose continued participation makes them unrepresentative of the target population.
The correct answer accurately identifies that the survey is based on an unrepresentative sample. By only surveying employees who voluntarily participated for at least six months, the consulting firm systematically excluded anyone who might have dropped out early because they found the program ineffective, unhelpful, or overly stressful. Therefore, the sample is heavily skewed toward those who experienced positive results.

Step-by-Step Solution

1
Analyze the argument's premises.
The premise relies on a survey of employees who voluntarily participated in a wellness program for at least six months, wherein 85 percent of these individuals reported positive results.
Identifying the specific evidence used to support the conclusion is the critical first step in finding the methodological flaw.
2
Identify the argument's conclusion.
The conclusion is that the wellness program is highly effective at improving overall employee well-being and should be implemented universally.
Understanding the broad scope of the conclusion is necessary to see if the limited premises adequately support it.
3
Evaluate the connection between the premises and the conclusion to find the logical gap.
The sample only includes people who stayed in the program for at least six months. It completely excludes anyone who found the program ineffective, overly difficult, or stressful and therefore dropped out early. Thus, the sample is inherently biased toward those who found it beneficial.
This reveals a classic survivorship bias, making the sample unrepresentative of the entire employee population.

Key Concept

Sampling Flaw (Survivorship and Selection Bias)
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Topics

Sampling and Survey Flaws

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