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How does a confidence interval differ from a point estimate?
AIt is always exactly equal to the population parameter
BIt only applies when the population standard deviation is unknown
CIt replaces the sample mean with the population mean
DIt is an interval of numbers rather than a single value
Answer & Solution
Correct answer: D. It is an interval of numbers rather than a single value
1. A point estimate is a single computed number, such as a sample mean.
2. A confidence interval instead reports a range of reasonable values for the unknown parameter.
3. That range is what makes it an interval estimate rather than a point estimate.
4. Options B and C attach conditions or substitutions that the general definition of a confidence interval never requires.
_Source: OpenStax Introductory Statistics (CC BY 4.0), Ch 8 "Confidence Intervals", section 8.1 A Single Population Mean using the Normal Distribution_
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