American Institute of Certified Planners (AICP) Practice Exam

What does a confidence interval provide an estimate of?

1. It provides the average score of a sample.

2. It provides a range that likely includes an unknown population parameter.

3. It provides the standard deviation of a sample.

4. It provides a fixed score value.

The correct answer is: It provides a range that likely includes an unknown population parameter.

A confidence interval provides a range of values that is likely to include an unknown population parameter, such as the population mean or proportion. This statistical tool is essential in inferential statistics, as it allows researchers to understand the degree of uncertainty associated with sample estimates. By constructing a confidence interval around a sample statistic, researchers acknowledge that the sample is only a subset of the population and that there might be variability in the population. The width of the confidence interval gives insight into the precision of the estimate—narrow intervals suggest more precision, while wider intervals indicate more uncertainty. This property of confidence intervals makes them invaluable for making inferences about a population based on sample data, providing an evidence-based way to estimate where the true population parameter likely lies.