The correct answer is OD: To calculate a point estimate, we need to know the sample size.
Let's break down why each statement is evaluated the way it is:
- OA. A sample statistic can never be equal to the population parameter.
- This statement is false. While it is rare, a sample statistic can indeed be equal to the population parameter if the sample accurately represents the population. For example, if you calculated the average height of all students in a small classroom, the sample mean could very well be the same as the population mean if the sample includes all students.
- OB. Point estimates are defined for both samples and populations.
- This statement is false. Point estimates specifically refer to estimates derived from sample data to estimate population parameters. Population parameters are true values by definition and do not need to be estimated.
- OC. To calculate a sample proportion, we need to know the population size.
- This statement is false. To calculate a sample proportion, we only need the sample size and the number of successes in the sample. The population size is not required for this calculation.
- OD. To calculate a point estimate, we need to know the sample size.
- This statement is true. Point estimates, such as the sample mean or sample proportion, are calculated using data from the sample. Knowing the sample size is crucial for these calculations and for understanding the reliability and variability of the point estimate.
Therefore, the correct statement is:
OD. To calculate a point estimate, we need to know the sample size.
