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A local television station conducts a call-in poll about a proposed city tax increase to buy park areas and protect them from development. Of the 2372 calls, 1921 support the proposal. We can't use these data as the basis for inference about the proportion of all citizens who support the tax increase. Why not?

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Final answer:

The data from the call-in poll is not a reliable source for making an inference about the general public's opinion on the tax increase due to potential self-selection bias, caller bias, skewed sampling, and coverage bias.

Step-by-step explanation:

We can't use the data from the local television station's call-in poll as the basis for inference about the proportion of all citizens who support the proposed city tax increase for several reasons:

  • The sample may not be representative of the entire population since it only includes individuals who felt strongly enough to call in. This leads to self-selection bias.
  • Caller bias exists because those who participate in such polls might have different opinions from those who don't engage with call-in polls.
  • The demographic of people who watch this television and are likely to call in might not reflect the broader population's demographics, leading to a skewed sampling.
  • The telephone poll might not have included cell phones, which excludes a significant portion of the population, leading to coverage bias.

To accurately infer the public's opinion, a random and unbiased sample of the entire population would be required. Additionally, response rate and sampling method significantly affect the reliability of polling as a measure of public opinion.

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