Research on the Historical Evolution and Hot Spots of Public Policy Making in China

Public policy formulation is the prerequisite and primary issue for public decision-making. This article uses the CiteSpace analysis software to make a detailed analysis of the research literature (1999–2019) on policy formulation in the CNKI database, and to sort out the historical evolution and hotspots of China’s policy formulation research in the past two decades. The analysis found that: policy formulation, educational policy formulation, interest groups, and public participation are the focus of research in the field of policy formulation; the first ten years mainly focused on relevant theories and experiences of Western countries, as well as sustainable development and harmonious society. The next ten years mainly focused on research on public opinion, democracy, think tanks, and satisfaction.

processes are relatively independent. The public policy as a product of the interaction between the policy subject and the environment and target groups will inevitably depend more on the behavior of the policy subject, that is, the policy maker. In order to make public policy formulation more reasonable, fairer and more effective, and to make policy content more able to reflect the public interests of society, the basic principles of rationalization, standardization, and democratization should be adhered to in the process of public policy formulation [1] .

Principles of public policy formulation 1.1 Principle of rationality
Rationality is one of the basic value orientations of modern public policy, and it is also a basic principle in the process of public policy making. Simon believes that in a broad sense, rationality refers to a way of behavior that is suitable for achieving specified goals within the limits of given conditions and constraints [2] . The action designed by "correctness" is that can seek the greatest success for the specified goal and its real situation [3] .

Principle of democratization
The democratization of decision-making is also an important value orientation in the formulation of modern public policies. It pursues social justice and emphasizes citizen participation. The formulation and implementation play a philosophical guiding role, and play an important role in regulation and coordination in the public policy field regulated by each [4] .

Keyword frequency and keyword co-occurrence
Keywords can reflect the essence of the research field and the content of the paper, and high-frequency keywords reflect the research hotspot and core of the field. It has been found that high-frequency keywords and hot keywords by recording the literature in the field of policy making include policy making, public policy, public policy formulation, education policy formulation, citizen participation, education policy, interest group, public participation (as seen in Table 1). For keywords in the field, the higher the intermediary centrality, the more important the node is in the network. From the table, it can be seen that the keywords policy making, public policy, public policy formulation, and education policy formulation have higher betweenness centrality, indicating that the policy making, public policy, and education policy formulation play a large role in literature research, which can be clearly seen from the frequency of occurrence.

Analysis of keyword time zone
In order to explore the changes in research hotspots as well as sustainable development and harmonious society. In the next ten years, the main focus was on research on public opinion, democracy, think tanks, and satisfaction.

Cluster analysis
In the clustering results, the Modularity value is 0.826, the larger of which, the better the network clustering. The value of Silhouette is 0.7129 < 1, which is closer to 0.7, indicating that the clustering effect has good reliability. It can be seen that the research on policy formulation centers on citizen participation, public interest, policy formulation, and public policy formulation.
Research on education policy, policy implementation, and value orientation is distributed all around in a radial way. First, through visual analysis, it is found that there are many hotspots in policy formulation research, and the existing results are scattered in various fields. However, from the main direction, they mainly focus on the research of citizen participation, public interest and education policy formulation.

Conclusion
This