Index, or statistical index, is an important statistical method to analyze the quantitative changes of social economic phenomena. It was produced in the second half of the 18th century, when gold and silver mined in the New World of America continued to flow into Europe, causing European prices to rise suddenly, which aroused widespread public concern. In order to measure changes in prices, economists began to try to compile price indices.

An index is a relative number that shows the dynamics of socio-economic phenomena. The index can be used to determine the total dynamics of socio-economic phenomena that cannot be directly added and compared; it can analyze the impact of changes in various factors in the total changes in social economic phenomena; it can be studied The effect of changes in the level of each group of indicators and changes in the overall structure in changes in the overall average index. The index is divided into individual index and total index according to the scope of the phenomenon reflected. The former reflects the relative number of changes in individual economic phenomena, such as the volume index of individual products, the price index of individual commodities, etc.; the latter is the relative number that shows changes in all economic phenomena, such as the industrial output value index and the consumer price index.



According to the different nature of the phenomenon reflected, it is divided into quantitative index and quality index.

The quality index is an index that describes the quality changes of economic activities, such as product cost index and labor productivity index.
According to the different calculation forms, it is divided into comprehensive index and average index. The former refers to the index calculated by comparing two total indicators, and the latter is a modification of the former.

The general relative number is the ratio of two related indicators, which can quantitatively reflect the comparative relationship between two related phenomena. There are many types of relative numbers, and they can be divided into two categories according to their manifestations: one is famous numbers, that is, relative numbers calculated by comparing two related absolute numbers or average numbers with different properties, generally There are famous numbers, and compound measurement units are often used. The other type is anonymous numbers, which can be expressed in multiples, percentages, coefficients, percentages, and thousandths according to different situations, such as birth rate and death rate. Relative numbers can be divided into five types, namely dynamic relative numbers, structural relative numbers, comparative relative numbers, intensity relative numbers, and relative numbers of planned completion levels, according to the nature of the compared indicators and their different functions.