1, the national trend school, also known as the narrative school, was born in Germany in the17th century. It is called the narrative school, because it mainly describes the significant problems of the country in words. Its main representatives are Hailmann Kang Ling and Ahenwal. Kang Ling was the first to teach the knowledge that political activists should have on the topic of "National Trend" at Tete University in Helms, Germany. Ahenwal was opened at the University of G? ttingen. His main work is "Outline of the National Conditions of Modern European Countries", which tells about "the remarkable matters of one country or most countries". He mainly studies and understands the national organization, territory, population, resource wealth, national conditions and national strength by means of comparative analysis, and compares the strength of various countries to serve the German monarchy. Because "national conditions" and "statistics" have the same meaning in foreign languages, they are officially named "statistics". This school is developing. It pays more attention to the explanation of the essence of things than the comparison and calculation of quantity, but it lays the economic theoretical foundation for the development of statistics. However, with the development of the capitalist market economy, the calculation and analysis of the number of things became more and more important, and the school later split into the chart school and the comparison school.
2. The School of Political Arithmetic The School of Political Arithmetic was born in Britain in the middle of17th century. Its founder is william petty (1623- 1687), and his masterpiece is the book Political Arithmetic, which he finished in 1676. Here "politics" refers to political economy, and "arithmetic" refers to statistical methods. This paper makes a systematic and quantitative comparative analysis of the national conditions and national strength of Britain, France and the Netherlands by using statistical methods such as numbers, weights and scales, which lays a methodological foundation for the formation and development of statistics. Therefore, Marx said: "william petty, the father of political economy, is also the founder of statistics to some extent." Another representative of the school of political arithmetic is john grant (1620- 1674). He used 1604 The Death Bulletin published once a week by the Church of London as the research data. 1662, he published the book Natural and Political Observations of Death Bulletin, and analyzed the relationship between the causes of death and population changes of London residents in recent 60 years. It was the first time that through a large number of observations, it was found that the sex ratio of newborns was stable and the proportion of different causes of death was a demographic law. For the first time, a "life table" was compiled to analyze mortality and life expectancy, which attracted widespread attention. His research clearly shows the important role of statistics as a national management tool.