What knowledge and insights have you learned after learning the course of Principles of Statistics? If you don't write less than 500 words, you will be rewarded 100. Answer quickly and beg on your knees. After nearly a semester's study, the strange name of statistics has gradually become familiar to everyone, and I have some feelings about this course. Before I studied statistics, when it came to statistics and data, a lot of boring figures and tables came to mind. At first, in my eyes, statistics was a very boring and monotonous subject. It does not emphasize reasoning and logic like mathematics, and only needs to collect raw data. But after studying this semester, I have a new understanding of statistics. Statistics is a methodological subject to study the characteristics and laws of population quantity under certain conditions. I began to realize that statistics play an important role in all aspects of social life. Before studying statistics, I always regarded statistics as another kind of mathematics, but after studying, I found that it was very different from mathematics. Statistics is closer to reality, and we are closely related to its practical significance in our study. Compared with data analysis, we can't do it like math. We must understand the actual economic significance of the analyzed data, so that our analysis is meaningful. Of course, I also saw the close relationship between statistics and mathematics. Many mathematical tools will be used in statistics, so we must review the relevant mathematical knowledge in order to use it flexibly in our study. Learning statistics can't be done piecemeal, but from a systematic and comparative perspective. Similarly, when learning hypothesis testing, we should compare the situation of a single population, two populations and multiple populations, and compare various preconditions of mean, variance and number. Summarize more, so that it is easy to understand memory, turn multiple formulas into several formulas, and reduce the burden of memory. In addition, when doing the problem, we must make clear the preconditions given in the question and correspond to different calculation methods. In fact, there are statistics everywhere in life, such as the annual census. To put it mildly, the statistical investigation of a commodity is produced by application and developed in the process of application. With the development of economy and society, we need to use data to reflect society and speak with data.