To determine the minimum necessary sample size to bestow confidence on public poll results in the United States, let's consider the common practices and statistical principles used in survey methodology.
1. Common Practice: In the context of public opinion polling, it is important to have a sample size sufficient enough to accurately reflect the views of the larger population. For nationwide polls in the United States, sample sizes typically range from 1000 to 1500 respondents. This range is widely considered to provide a good balance between reliability and practicality.
2. Statistical Principles: The principles of statistical sampling suggest that a sample size of around 1000 is generally enough to ensure a margin of error of about ±3 percentage points for a population the size of the United States, with a confidence level of 95%. This level of precision allows pollsters to make reliable inferences about the larger population.
3. Confidence and Variability: The confidence in poll results is tied to the concept of sampling error and variability. By having at least 1000 respondents, pollsters aim to capture the diversity of opinions and reduce the error margin.
Given these considerations, the minimum sample size generally deemed necessary to bestow confidence on public poll results in the United States falls within the range of 1000 to 1500 respondents.
Therefore, the correct answer is:
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1000-1500
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