红色好像不是总体均值的意思？

问题如下：

A financial risk analyst at a real estate firm is preparing a report on housing prices. The analyst compiles the summary statistics for a dataset with 25 observations and decides to use bias-corrected estimators of the parameters due to the sample size. Which of the following correctly describes the bias of an estimator?

选项：

A.The bias is typically calculated by taking the square of the deviation between two mean estimators.

B.The bias is greatest when the expected value of the estimator is equal to the true population value being estimated.

C.The bias is equal to the expected value of the estimator divided by the population value being estimated.

D.The bias is the difference between the expected value of an estimator and the true value of the population parameter.

解释：

Explanation: D is correct. The bias of an estimator θ is defined as:

Bias(θ) = ​

Where θ is the true value of the parameter that we are estimating. It measures the difference between the expected value of the estimator and the population value being estimated.

A and C are incorrect. As explained above, bias is calculated as the difference between the expected value of the estimator and the population value being estimated.

B is incorrect. When the expected value of the estimator is equal to the true population value being estimated, bias is zero.

Learning Objective: Describe the bias of an estimator and explain what the bias measures.

Reference: Global Association of Risk Professionals. Quantitative Analysis. New York, NY: Pearson, 2023, Chapter 5, Sample Moments [QA-5].