What term describes a descriptive measure computed from a population?

• A. Number of observations in a population
• B. Mean of a population
• C. Sum of all observations
• D. Number of observations in a sample

Answer: (A)

The main idea is that a descriptive measure taken from the entire group describes the population’s characteristics. The most direct descriptor of a population is its size—the number of observations it contains—which is the population count N. This tells you how big the group is, a fundamental property of the population itself. While the mean or the sum describe aspects of the data values, and the last option describes a characteristic of a sample rather than the whole population, the count of observations in the population best fits the idea of a basic descriptive measure of the population as a whole.