Examkin

Question

Difficulty: HardStatistical Sampling and Studies

A county health department is evaluating a new public health program designed to lower blood pressure among residents with hypertension. The county has 120,000120,000 adult residents, of whom 30,00030,000 have been diagnosed with hypertension. The department selects a random sample of 400400 adults diagnosed with hypertension from a list of patients at a major county clinic to participate in the program. After six months, 280280 of the participants show a significant reduction in blood pressure. Which of the following is the most appropriate conclusion?

  1. The program is likely to be associated with a significant reduction in blood pressure among adult residents with hypertension who are patients at this major county clinic.Answer
  2. B
    The program is likely to be associated with a significant reduction in blood pressure for all adult residents of the county.
  3. C
    The program is likely to be associated with a significant reduction in blood pressure for all 30,00030,000 adult residents of the county who have hypertension.
  4. D
    It can be estimated that exactly 2,1002,100 adult residents in the county with hypertension would show a significant reduction in blood pressure if they participated in the program.

Answer

The program is likely to be associated with a significant reduction in blood pressure among adult residents with hypertension who are patients at this major county clinic.
The correct answer is correct because the sample of participants was randomly selected from patients diagnosed with hypertension at a specific major county clinic. Therefore, the findings can be generalized to the population of patients with hypertension at this specific clinic.

Step-by-Step Solution

1
Identify the population from which the sample was selected.
The sample of 400400 adults was randomly selected from the patients diagnosed with hypertension at a single major county clinic.
Results of a study can only be generalized to the population from which the sample was randomly selected.
2
Determine the limits of generalization for the study's findings.
Because the sample was only drawn from patients at this specific clinic, the findings cannot be generalized to all adults in the county or even to all adults in the county with hypertension.
Patients at one clinic may not be representative of the entire county's population or all individuals with hypertension in the county.
3
Evaluate the options based on these generalization rules and mathematical accuracy.
The option proposing a significant reduction in blood pressure for patients at this clinic is valid. The options generalizing to the entire county or all hypertensive county residents are invalid due to sampling bias. Stating that exactly 2,1002,100 residents would benefit is both an invalid generalization and mathematically incorrect since 70%70\% of 30,00030,000 is 21,00021,000, not 2,1002,100.
This confirms the correct option matches the sampling frame and avoids unwarranted extrapolation and arithmetic errors.

Key Concept

Generalization in observational studies and surveys requires that the sample be randomly selected from the target population.
Rate this question

Topics

Statistical Sampling and Studies

More questions from this topic