The econometric model contains one or more stochastic equations, which concisely and effectively describes and summarizes the quantitative characteristics of a real economic system, and more profoundly reveals the quantitative change law of the economic system. It consists of a system or an equation, and the equation consists of variables and coefficients. Among them, the system also consists of equations. Econometric model reveals the quantitative relationship among various factors in economic activities, which is described by stochastic mathematical equations.

Broadly speaking, everything includes economic, mathematical and statistical models;

In a narrow sense, only the mathematical statistics methods of parameter estimation and hypothesis testing are used to study the model of empirical data.

Using cross-sectional data as sample data of econometric model, we should pay attention to the following problems. One is the consistency between the sample and the matrix. Mathematically speaking, the parameter estimation of econometric model is to estimate the parameters of the matrix with individual samples randomly selected from the matrix, so it is required that the matrix and individuals must be consistent. For example, to estimate the production function model of coal enterprises, we can only use the data of coal enterprises as samples, not the data of coal industry. Then, the cross-sectional data is difficult to estimate some set models. For example, if the production function model of coal industry is established, the appropriate cross-sectional data cannot be obtained.