Statistics is a science about data. All the collected data need to be sorted out and analyzed before a conclusion can be drawn, which is the whole process of statistics using data to solve practical problems. However, you will find that the same data can be analyzed by different methods and different conclusions can be drawn, and different data can also be analyzed by the same method. Such as weather forecast, different forecasting agencies have different forecast results. Moreover, the conclusions drawn from statistical analysis are often uncertain (Uncertainty), because it often describes the opportunity of something happening, which can be measured by probability. For example, the probability of precipitation in the weather forecast, as we all know, if the probability of precipitation is as high as 90%, it is likely to rain. If the probability of precipitation is only 5%, everyone will think that it will hardly rain. But it won’t rain in the actual situation, and we can only know when the predicted day really comes.
Statistics focuses on the quantitative characteristics of a large number of repeatable things. This is because in some fields, some conclusions are difficult to be described with certainty like mathematical formulas or theorems. For example, when parents are taller, most people think that their children will be taller. But when you observe the height of a parent and their children, you will find that some parents who are taller are not tall. Therefore, height has a certain randomness (randomness）。 This randomness may be related to human genes, living environment, acquired diet, living habits and other factors. However, on the whole, the height of children of taller parents tends to be higher, which has long been confirmed by the experimental data of Gao Erdun (1822-1911), a famous British biologist and statistician, in 1855. It is random that a person’s height may be different. But on the whole, the stability of average height shows that there is a law in randomness, which is the statistical law. Therefore, it can be further said that statistics is also a knowledge of finding out statistical laws.