Why is a sample used more often than a population when estimating a population proportion $p$?

• A. Because a sample always gives the exact value of the population proportion $p$.
• B. Because population data is not useful for statistical inference.
• C. Because samples are always more accurate than population data.
• D. Because collecting data from the entire population is often impractical or too costly.

Answer: (D)

Verified step by step guidance

1. Understand the difference between a population and a sample: A population includes all members of a specified group, while a sample is a subset of that population.
2. Recognize that collecting data from the entire population (a census) can be very time-consuming, expensive, or even impossible, especially for large populations.
3. Know that samples are used to make inferences about the population because they are more practical and manageable to collect.
4. Remember that statistical methods allow us to estimate population parameters (like population proportion) from sample statistics, along with a measure of uncertainty.
5. Therefore, a sample is used more often than a population because it provides a feasible way to estimate population characteristics without the need for complete data collection.