**1. Introduction**

**Econometrics** is an economics discipline based on certain economic theory and statistical data, uses mathematical and statistical methods and computer technology, in order to establish the econometric model as the main means, quantitative analysis with random characteristics of the relations between economic variables. The main content includes theoretical econometrics and applied econometrics. How to use, transform and develop the methods of mathematical statistics to make it a special method for the determination of stochastic economic relations. Applied econometrics is under the guidance of a certain economic theory, in order to reflect the statistical data of the facts as the basis, the use of econometric methods to study the economic and mathematical model of the practical or to explore the empirical economic law.

Econometrics takes mathematical economics and mathematical statistics as the method basis, for the economic issues to close to the number of theoretical and empirical (empirical) close to the number of the two comprehensive and branches of economics.

The basis of econometrics is a set of measurement methods based on mathematical statistics theory. The main purpose or purpose of econometrics is mainly two aspects:

1) Theory test. This is the most important and reliable use of econometrics. This is also a main content of econometrics itself.

2) Forecast application. From the ultimate goal of theoretical research and methods, the prediction (including policy evaluation) is of course the final task of econometrics.

**2. Characteristics**

Model types: a stochastic model. Model oriented: a model based on economic theory.

Model structure: the relationship between variables is linear or can be linearized, which belongs to the causal analysis model, the explanatory variables have the same status, and the model has a clear form and parameters.

Data type: the time series data or cross section data is the sample, and the explanatory variables are continuous random variables that obey the normal distribution.

Estimation method: using only the sample information, using the least squares method or the maximum likelihood estimation of variables.

**3. Research Objects**

Two research objects of econometrics: cross sectional data and time-series data. The former aims at induction of different economic actors have similar behaviors relevance, to model parameter estimation results show correlation; while the latter focuses on the analysis of the same economic actors at different time of the data, in order to show the dynamic behavior of the object of study.

Emerging econometric study begins to cut with cross section and time series data at the same time, in other words, each cross-section has time series of observations and the data known for tracking data (panel data, or panel data analysis). Tracking data to study the dynamic behavior of multiple different economies, we can obtain more abundant empirical conclusions than the simple cross section or time series analysis.

**4. Learning Methods**

Compared with the general mathematical methods, the econometric methods have very important characteristics and significance:

1) The research object has changed greatly. From the study of the uncertainty of the problem to the uncertainty, the nature and significance of the object will be a huge change. Therefore, in the way of thinking, the method of the nature and the method of the results will be new change.

2) The research methods have fundamental changes. The basis of econometric method is probability theory and mathematical statistics, and it is a new mathematical form. In learning to pay attention to its basic concepts and methods of understanding and grasp, to fully understand the method and other mathematical methods of the fundamental difference.

3) The results of the study have changed.

**5. Theoretical Econometrics and Applied Econometrics**

Theoretical econometrics introduces and examines the econometric theory and method as the main content, focusing on theory and method of mathematical proof and derivation, and mathematical statistics contact is very close. Econometric theory studies special model estimation method and testing of the model in addition to the mathematical theory of econometrics model and universal application of the econometrics model parameter estimation and test methods.

Applied Econometrics takes establishing and application econometric model as the main content, emphasizes the application model of economics and economic statistics based, focused on building and application model in the process of practical problems.