In postgraduate mathematics, the numerical characteristics of random variables are a very important chapter, which is tested every year, so everyone should master the different calculation methods of numerical characteristics skillfully.

The basic numerical characteristics include: mathematical expectation, variance, covariance and correlation coefficient. In the part of mathematical statistics, we often need to calculate the numerical characteristics of statistics. Compared with the numerical characteristics of ordinary random variables, the calculation of statistical numerical characteristics is relatively complicated, and many students find this part of knowledge difficult to learn. Let's do some analysis for your reference.

Introduction to commonly used statistics

Among all kinds of statistics, there are two most basic and important statistics. One is the sample mean, which is both an unbiased estimate and a consistent estimate of the population mean, and the other is the sample variance, which is also an unbiased estimate and a consistent estimate of population variance. No matter what distribution the population obeys, this conclusion holds; It can also be seen from Example 2 that the sample mean may be a more effective estimate than other statistics, that is, its variance is smaller.

The above analysis is expected to help you master the calculation method of statistical numerical characteristics, and finally I wish you a complete success in the postgraduate entrance examination.

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