Final answer:
A statistic is a characteristic of a sample, while a parameter is a trait of a population. Option d. sample, population is the correct fill-in for the student's question.
Step-by-step explanation:
The correct answer to the student's question is d. sample, population. A statistic is a numerical characteristic that represents a property of a sample. It is used as an estimate for the corresponding parameter of the overall population. For instance, the average test score of a classroom can act as a statistic representing that particular sample of students. Conversely, a parameter is a characteristic that describes an entire population; for example, the average test score of all students in a school district could be considered a parameter if data from all students is available.
A simple way to remember the difference is that a parameter pertains to the whole population while a statistic applies to a sample taken from that population. The calculation of statistics helps in the analysis of data when it is not feasible to collect information from every member of the population. In statistical modeling, we often use the information gathered from a sample to make inferences about the population, thereby employing statistical models that account for variability and probability distributions.