Think Tanks’ Influence on the Front-End of the Policymaking Process: Empirical Evidence from the United States

One of the most important goals for think tanks is to influence the public policy. Therefore, the way that think tanks influence the process of making public policies is worth thinking about. It is widely known that the United States has the largest number of and most influential think tanks in the world. Paying more attention to the front end, this paper chose to focus on the policy process perspective to analyze the think tank’s influence on the public policy by using the United States as an example. Referring to the “Multiple-Streams” theory, this paper built a mechanism framework from the perspectives of the problem stream, the policy stream and the political stream. Furthermore, this paper used the example of three typical types of think tanks from the United States to deeply analyze the location and the influential patterns of the think tanks. Which are the academic type, contract type and advocacy type. Think tanks have very important influence on the public agenda setting. In this process, think tanks are usually with the help of media and public opinions to influence the problem stream, with the help of their own research ability and reputation to influence the policy stream, and with the help of the core departments’ personal exchange to influence the political stream. Different types of think tanks focus on different aspects and make the process of formulating public policies in the United States more scientific and rational.


Introduction
Think tank is a place where ideas are produced and stored. One of the main goals of the think tank is to influence public policy directly or indirectly via a variety of channels and means in the short or long term. In recent years, with the increasing emphasis on scientific and effective decision-making in various countries globally, think tanks around the world are bracing for a new wave of development. According to the latest global think tank report compiled by a non-profit program at the University of Pennsylvania in Philadelphia, the Think Tanks and Civil Societies Program (TTCSP) [1], there were 7815 think tanks worldwide in year 2017, among which the United States led by 1,872. With the largest number of think tanks in the world, how exactly do think tanks influence American public policies are the focus of this paper.
To address the issue of "the influence of think tanks on public policies", researchers can approach it from many perspectives. From the perspective of policy types, researchers can explore the influence of think tanks on politics, economy, society, science and technology, diplomacy and other types of policies respectively. From the perspective of policy process, researchers can analyze the impact of think tanks on the formulation, implementation, evaluation, supervision and termination of policy making process respectively [2]. From the perspective of policy term structure, researchers can observe the short, medium and long-term effects of think tanks on policy. Classification from the perspective of "impact" can also include the impact pattern, field and degree. The purpose of all the classification is to make analysis logic more clearly. The existing research on related subjects can be summarized in the above categories, and the research on the impact of American think tanks on public policies is also the same. The peak period of academic research on American think tanks appeared in the 1990s, and the definitions of the concept, category and function of think tanks were also the general focus of researchers. The functions of American think tanks are mainly focused on the production of policy thoughts, providing policy solutions, cultivating reserve talents, and serving the public in education [3,4]. In order to explain the role of think tanks, the corresponding theoretical positions should be selected first. The meritocracy believes that the elites of power dominate the formulation of policies [5]. Therefore, the think tank experts as "policy elites" influence the decision-making more through the relationship with the "political elites" [6]. While pluralism believes that policy is the result of the balancing of interests [7]. The role of think tanks is more influenced by the game among various interest groups and policy participants. The growing tendency of think tanks to focus more on the issues of financial support and market demand has led to the doubling of the number of American think tanks but the stagnation of their influence [8].
In terms of research content selection, most existing studies are based on abundant cases and detailed data, so as to deeply analyze how think tanks play roles in different policy subsystems such as diplomacy, tax reform and medical reform [9], and explain how think tanks use various mechanisms to expand their influence at different stages of the policy process [10][11][12], such as the "knowledge exchange", "interlocking directors", "revolving door" and other important mechanisms. American think tanks are large in number and many in types. On the basis of previous studies, this paper chooses to analyze only one aspect of American think tank's influence on public policy from a single perspective, and aims to build a theoretical framework for this analysis perspective. This gives a systematic induction of previous studies, on one hand, and on the other, it also provides reference for later studies from the same perspective. In analyzing the role of think tanks and policy experts, Andrew Rich pointed out that the academic advisory role of experts is more reflected in the early stage of policy agenda setting, and only provides a so-called justification for decision makers in the later stage [8]. This paper thus chooses to focus on the front end of the policy making process, and takes American think tanks as example to analyze the impact of think tanks on public policies. Based on the existing literature, it can be seen that the influence of American think tanks on policy covers various fields and varies in degree, but has many similarities in the way. In view of this, this paper mainly focuses on the ways and channels of influence on policymaking process, but less on the areas and degree of influence on public policies.

The Foundation of the Multiple-Streams Approach
The Multiple-Streams Approach was proposed by John W. Kingdon in the book Agendas, alternatives, and Public [13]. Through four years of fieldwork and research, Kingdon has opened a "black box" at the forefront of policymaking. He presented us through a series of real cases of how could a public issue become a public policy in American policymaking process. It can be seen that the Multiple-Streams Approach mainly focuses on the establishment process of the policy agenda, which is the front end of the whole process. According to Kingdon, there are three different and independent streams in the public policy system, namely the Problem Stream, the Policy Stream and the Political Stream. At a critical point, the three streams would converge to push the policy window open, and the policy agenda is launched from then on. This is a key stage in which a policy can be established, and it is the most dramatic stage of conflict. Moreover, the main function of the think tanks is to spread ideas to public policy makers. Which means the most important time point for think tanks to exert its influence is before the public policy issued. Therefore, this paper focuses on the front end of policy process and discusses the role of think tanks in it. Based on this, this paper analyzes the three aspects of steams by the classification method in the system of Multiple-Streams Approach, and establishes the theoretical framework at the same time.

The Problem Stream
There are numerous of public problems in the society. Among these problems which can be concerned about by policy makers are mainly promoted by media exposure and public opinion. These are undoubtedly two important ways to connect with each other. Therefore, the focus of analysis for this part will emphasize on the role of think tanks in influencing media publicity and guiding public opinion.

The Policy Stream
As described by Kingdon, "many ideas float around in this policy primeval soup, the ones that last, as in a natural selection system, meet some criteria. Some ideas survive and prosper; some proposals are taken more seriously than others." Therefore, the interpretation of these survival ideas in this process should start more from the think tank itself, in which the level of researchers and products quality play a crucial role. It is also an important aspect of further promoting such products to attract the attention of the core layer of policy makers effectively.

The Political Stream
This part mainly involves some changes of the government or the congress itself, such as the changes of the majority party in the congress, the adjustment of key personnel in the government and so on. Therefore, from this perspective, this paper mainly focuses on the relationship between the think tank and the government, congress or other authorities. Different from the Policy Stream, analysis of the Political Stream is more concerned about the interaction between the think tank and the core layer from the perspective of personnel changes rather than policy view.
Combined with the positioning of the above three aspects, this part can draw the analysis model diagram shown in figure 1. In the following sections, a more in-depth discussion of the impact of the US think tanks on the setting of the public policy agenda will be conducted in accordance with this model, as described above, mainly from the perspective of the channels and patterns of the influence.

Analysis of the Influence Patterns
Based on the Multiple-Streams Approach

Influences on the Problem Stream
From the perspective of the Problem Stream, the think tank mainly uses media publicity and guides the direction of public opinion to put its concerns on a prominent position, so as to make some problems more visible. Media communication and public opinion have been complementary and mutually influencing. The influence pattern of think tanks on policy agenda setting can be realized through two channels, which are through the cooperation with the media to influence the public opinion direction, or through the interaction with the public to attract the media attention.
The cooperation between think tanks and media is a process of shaping their public images. With the rapid development of internet and information dissemination, the United States, at the forefront of scientific and technological development, will undoubtedly make full use of these convenient means. Think tanks usually adopt the combination of New-Media and We-Media to promote influence. On one hand, the experts and scholars of the think tank often use the way of making comments on the mainstream media, creating columns and enhancing the exposure rate. For example, they may debate or analyze a certain issue on TV, or they may make comments in the newspaper. Think tank experts can be seen in America's best-known broadcasters, including ABC, NBC, FOX, CNN, and in the most popular newspapers, including the Wall Street journal, the New York times, the Washington post and the Los Angeles times. On the other hand, in order to better attract the attention of the younger generation, think tanks have also begun to use We-Media channels such as Facebook, Twitter, YouTube and even mobile Application to spread ideas and improve its impact.
Think tanks typically interact with the public in two broad categories. One is through publications. In addition to the articles published by researchers in various journals, newspapers and magazines, the major think tanks in the United States also publish a large number of periodicals, monographs, research reports and other types of publications every year. The publications of many famous think tanks have exerted long-term and far-reaching influence. The other is by holding various seminars, lectures, and training activities. American think tanks often hold large and small meetings for the sake of discussing hot issues and releasing research results. For those well-known think tanks, holding hundreds of meetings a year is the normality, and most of these meetings are open to the public. In addition, the development of the internet also provides convenience for the public to accept such information. If they cannot be at the scene by person, the public can also obtain relevant information through the internet. These seminars sometimes also attract the media to attend. Additionally, short-term training programs are also an important way for think tanks to guide the public.

Influences on the Policy Stream
From the perspective of the Policy Stream, the influence of think tanks mainly lies in how they can properly and powerfully prove the effectiveness and feasibility of their ideas or proposals through their professional research capacity. This is undoubtedly a high standard requirement for the think tank itself. Firstly, there are more than 1,800 think tanks in the US as a whole [1], so it is no exaggeration to say that the research area of the American think tank has fully covered the scope of its public policy. professional think tanks or comprehensive think tanks engaged in relevant research on political, economic, scientific and technological, medical, military, education and other fields. Although different think tanks have different research priorities, they are same in how to make their solutions stand out. Generally speaking, there are mainly three effective ways.
Firstly, build a high-level research team. Most think tank researchers are trained professionally in a particular field, and most have doctor or master degrees. Gradually, many think tanks do not only focus on scientific research, but also add many practical contents. Based on this, some practical talents with strong motivation also join the think tanks, such as some retired politicians, entrepreneurs and social activists. However, regardless of the personnel structure of various think tanks, their knowledge elites' characteristics and the original intention of providing high-quality research products are consistent. Only by ensuring high standards and high quality of research results first, can policy makers' choices be further influenced. At the same time, the think tank also attaches great importance to the cultivation of the new generation of researchers. For example, through internship programs, or even directly setting up their own graduate schools, the younger generation can improve their ability in practice and study, experience their talents, and better inherit the mantle of their predecessors.
Secondly, communicate directly with the core layer. In this regard, American think-tank experts can communicate with government officials directly through the way of give speeches to the government, writing letters to political leaders, submitting briefings and research reports and even serve as advisers to the executive agencies. For example, Bill Frenzel of the Brookings Institution and C. F. Bergersten of the Peterson Institute for International Economics both served as additional advisers to Advisory Committee for Trade Policy and Negotiations of the Office of the United States Trade Representative.
Thirdly, testify at congressional hearings. Congressional hearings are a unique design in the US policy process, and the passage of a bill has to go through various hearings held by committees of the house and senate. The hearing is a key part of whether a policy idea can finally become a formal policy after all the previous efforts are taken seriously. Otherwise, if other opinions exist, the hearing can also be an important place for think tank experts to promote alternatives. Members of congress and different stakeholders express their opinions and views based on election considerations, political positions and values [14]. And think tank experts are often invited by congress to testify at hearings, in a way that not only directly affects members of congress, but can also shape powerful political opinion.

Influences on the Political Stream
From the perspective of the Political Stream, the influence of think tanks is mainly reflected in the presidential transition and personnel adjustment, which can be realized through serving as an advisor to the US presidential candidates and through the distinctive "revolving door" mechanism, and the two aspects are mutually complementary. Additionally, think tanks' advice for presidential candidates can be conveniently and directly used in the publicity campaign to spread their ideas. On one hand, the turning point of presidential transition promotes the surging of political stream, on the other hand, it also brings some policy hot spots to the front desk. The influence of the "revolving door" mechanism is more long-term, and its influence on the interpersonal network can be throughout the entire policy process. As the name implies, the "revolving door" is the door between the government and the think tank. And the greater influence on the political stream is undoubtedly from the door of the think tank into the door of government, which is to achieve personnel adjustment. Usually, the period which a new government takes the stage is also a critical period for personnel adjustment in administrative system, and those think tank scholars who have played a key role in the presidential campaign are often transferred to the government and get full attention when the new president forms the cabinet.
Thus it can be seen that American think tanks have exerted important influence throughout the whole setting process of the policy agenda, and the channels of influence are diversified. Above, this paper rely on the Multiple-Streams Approach to analyze the think tanks influence from the perspective of three streams. Next, this paper will apply the Multiple-Streams Approach to the analysis of specific cases of think tanks. The positioning of different types of think tanks in the framework should be different.

Classification of American Think Tanks
American think tanks vary widely in size, funding sources, structure and research areas, so there are many different ways and perspectives to categorize them. For example, categorizing based on their affiliation, organizational structure, policies and philosophical tendencies etc. This paper selects the classification method of James G. McCann, the leading researcher of the TTCSP. He divided the American think tanks into three types, which are academic type, contract type and advocacy type [15]. These three types of think tanks can correspond to different stages of the development of American think tanks. Academic think tanks can roughly correspond to the first generation of think tanks produced in the progressive era of the United States in the early 20 th century. During this period, the United States was in the stage of rapid development and transformation. Various social contradictions and problems were prominent. Therefore, the government eagerly needed experts and scholars to make suggestions. Based on this, think tanks in this period mainly existed as policy research institutions. The second category of think tanks could correspond to a batch of government-contracted think tanks that emerged from the end of world war Ⅱ to the 1960s. In order to maintain its hegemony in the struggle with Soviet Union, the United States needed professional engineers and scholars to provide ideological and technical supports. Therefore, most of the think tank researches in this period focused on the field of military industry. The third generation of think tanks mainly appeared in the 1970s and 1980s. The development of international situation during this period made the think tanks have a strong ideological feature, so they were called as advocacy think tanks. In the following, this paper discussed the characteristics and typical representatives of the three types of think tanks in the Multiple-Streams Approach.
Academic think tank is also known as the university without students, and The most representative ones include The Hoover Institution on War, Revolution, and Peace founded in 1919, The Brookings Institution founded in 1927, and the Fairbank Center for Chinese Studies founded in 1955. Researchers at such think tanks are academically advanced and the institutions are funded largely by donations from foundations, enterprises and individuals. They are committed to applying scientific knowledge to research and to solving a wide range of public policy problems. Their research has strong independence and objectivity. Therefore, the main goal and mission they pursue is not to directly influence policy-making, but to produce high-quality research results.
Its more of a principal-agent relationship between contract think tanks and the government. The type of contract think tanks are typically represented by the RAND Cooperation founded in 1948 and the Urban Institute founded in 1968. The government will sign research contracts with think tanks based on their demand and the results would be presented directly to the government in the form of reports, which are rarely open to public. Due to its special relationship with the government, the research funds of the contract think tanks mainly come from the government, but this does not affect the objectivity and scientificity of their research results. Their duty is to provide the government with high-quality research reports that can directly solve the pressing problems in reality.
Advocacy think tanks have big differences with the two types of think tanks discussed above, which are characterized by distinctive partisan and policy orientations, such as the Heritage Foundation founded in 1973 and the American Enterprise Institute for Public Policy Research founded in 1977. Most of their funds come from large enterprises and financial groups related to the interest groups or parties. And their main purpose is not to study the policies themselves, but to promote political ideas, win the current policy debate, and then help the party they support to achieve the corresponding political goals. Therefore, the objectivity of this type of think tanks research is questionable.

Three Types of Think Tanks' Positions in the Multiple-Streams Framework
In the next section, this paper selected the most representative think tanks of the three types as examples to further analyze the specific positioning in the Multiple-Streams Framework, which are the Brookings Institution, the RAND Corporation and the Heritage Foundation. Firstly, the basic information of the three types of think tanks is briefly introduced, as shown in table 1. In the United States, think tanks' scale is not very large. A think tank with more than 100 people can be called as a large think tank. Therefore, the size of all of the three think tanks as examples is absolutely remarkable in terms of their staff numbers alone. In addition, the research fields of the three think tanks are also comprehensive and diversified, with a full range of research area. Among them, the Brookings Institution is relatively more focused on the public policy field, RAND is more focused on the military and scientific fields, while the Heritage Foundation in recent years has been more focused on the basic fields of politics, economy, and some urgent policy researches. Combined with the above discussion of each types of think tanks characteristics, the role that each think tank plays in the Multiple-Streams Approach can be summarized as follows. As shown in table 2, positioning in the Problem Stream, the focus of a think tank is to make some problems more visible and thus develop them into issues. But there is no such concern for contract type think tanks. The subjects they study are already the most important aspect that policy makers concerned. Positioning in the Policy Stream, a think tank's starting point is to make its policy options to be valued and recognized by the policy maker. However, the academic type think tank usually first focus on the scientificity and objectivity of their research achievements. Research reports under such principles are absolutely guaranteed in quality, but are unlikely to catch the eye of policymakers in the short term. Nevertheless its long-term influence cannot be underestimated. Positioning in the Political Stream, think tanks are primarily concerned with internal exchanges with people in power centers. As for the advocacy type think tanks, they already have close relations with their supporting parties, furthermore, their members even have close personal relations with government officials, such advantages cannot be achieved by the other two types of think tanks.

The Brookings Institution
The Brookings Institution is one of the world's most famous think tanks, and for many years it is the most influential think tank in the United States. It is also the first non-profit organization in the US to conduct research on public policy. It based in Washington, D. C., and has branches in many countries around the world. Based on the contents in table 2, analysis of the Brookings Institution focuses primarily on Problem and Political Stream, while the Policy Stream that are relevant to the quality and research level of the think tank itself will be less concerned here in this case analysis. This is not to say that the Brookings Institution does not pay attention to this aspect, but that its research ability and quality have already been integrated into its blood stream, and become the cornerstone of its success and the worldwide fame. In the introduction of its official website, "quality", "independence" and "impact" are most prominent. By virtue of its reputation, the institute can continuously attract global talents to join in and work for it. The research agenda and recommendations of Brookings's experts are rooted in open-minded inquiry and over 300 scholars from all over the world who provide the highest quality research, policy recommendations, and analysis on a full range of public policy issues. And as mentioned earlier, short-term impact on policy is not its primary goal.
As for the influence on the Problem Stream, there are three main aspects of performance. Firstly, Scholars at the Brookings Institution have been keeping a high profile in American mainstream media. During the Gulf War, Brookings scholars made as many as 14 appearances on US TV show within a month. In terms of media citations, the Brookings Institution has consistently topped the list, occasionally slipping to the second place. With the development of technology, especially the development of mobile intelligence, smart phones have become the main tool for people to acquire information. For this reason, the Brookings Institution has released applications that can run on iOS, Android, Symbian and BlackBerry OS, which basically covers all the user groups. Secondly, in terms of publications, the Brookings Institution publishes about 50 new books per year, and it has its own press. In respect of periodical publications, the Brookings Review (quarterly), the Brookings Papers (such as the annuals Brookings Papers on Education Policy) have become the representatives of the American think tank publications. In addition, numerous of papers, articles, reports, policy briefs and opinion pieces are produced by Brookings research programs, centers, projects and, for the most part, by experts. Meanwhile, the institution's research findings are regularly published and updated on its official websites, Facebook and Twitter accounts. Thirdly, in terms of public activities, the Brookings Institution hold hundreds of seminars and conferences around the world every year, so as to promote the communication of public opinion and the publicity of the institutions' achievements.
As for the influence on the Political Stream, throughout its nearly 100 years of history, the Brookings Institution, which has insisted on nonpartisanship and intellectual independence, has played an important role in the succession and smooth transition of power in the United States. In terms of revolving doors, former President Barack Obama had 32 Brookings scholars in his administration, the most famous one Susan Rice was the former national security adviser. And as for the current president Donald Trump, the Brookings Institution has offered four resources to help measure and contextualize the president team's turnover and released a report of Tracking Turnover in the Trump Administration [19].

The RAND Corporation
RAND, the Research and Development Corporation, is based in Santa Monica, California. It originated in 1946 as the "RAND program" to promote links between the US military, government intelligence, industry and universities. In view of the fact that most of the RAND researches are directly commissioned by the US government and military, there is no need to devote too much energy to issue selection and public opinion guidance, but more to how to produce high-quality research results. Therefore, this paper will focus more on RAND's research and management characteristics.
As for the influence on the Policy Stream, the focus of the think tank is to make its own solutions as acceptable and technically feasible as possible while ensuring objective, independent and high quality. In this regard, RAND has always had a set of strict research standards, covering research problems, purposes, methods, data, assumptions, policy recommendations and other aspects, And clearly stipulated that the language used should be accurate while being as simple as possible, and the research results should be eye-catching and have practical value. These are important aspects of ensuring that research proposals stand out. At the same time, RAND also had a rigorous internal quality review mechanism for its own research project, and inspectors were "outsiders" who did not participate in the project to ensure objectivity and impartiality. In the specific research process, RAND attaches great importance to cross-disciplinary researches. The members of RAND have diverse backgrounds and rich experience, and more than 60% of the researchers have doctorates. In view of the same research program, RAND will develop a variety of solutions based on the disciplinary characteristics of experts and scholars in different fields to give play to their complementary advantages. In addition, RAND also pays attention to the combination of education and scientific research. It has its own graduate school [20], where students can participate in the company's research projects as interns and inject young blood into the company.
As for the influence on the Political Stream, RAND has maintained close cooperation and intelligence sharing with the US military and government based on their commission and financial support. Meanwhile, RAND is also tasked with developing and delivering technical talent to the military and government. This is also part of its graduate school functions. Therefore, this long engagement has ensured the RAND corporation's enduring influence on the American power system.

The Heritage Foundation
The Heritage Foundation is the leading policy research organization for the new right-wing government in the US, based in Washington, D. C. The foundation has a strong ideological and partisan tone, and its basic argument is conservative rhetoric, which advocates small government and nonintervention to defend traditional American values. It is the republican stronghold and maintains close ties to the White House. Joseph Coors, co-founder of the foundation, was a key member of Reagan's "kitchen cabinet". As a representative of an advocacy think tank, the Heritage Foundation 's main goal is to sell its policy ideas. But based on its partisanship, the revolving door opportunities for foundation members usually occur during the republican party's rise to power. Therefore, the analysis of the Heritage Foundation in this paper will focus more on its propaganda means and influence.
As for the influence on the Problem Stream, few think tanks in the US have invested as much energy in media relations as the Heritage Foundation, which typically accounts for more than 20 percent of total budget expenditures, and it has paid off. As a late established and relatively small think tank, the Heritage Foundation's influence in the media industry has been closely followed by the Brookings institution and the RAND corporation. Whether cited by national media (TV, newspaper, magazine) or by mainstream American TV news (ABC, NBC, CNN, CBS, FOX), the foundation ranks in the top 5, and is firmly at the head of the advocacy think tanks. Researchers from the foundation receive hundreds of interviews every year. And the foundation started political talk shows on television in the 1990s. In recent years, it has also been actively using the Internet to spread its ideas. At the same time, the foundation also used the network platform to collect research data, for example, by establishing the "online statistics" and other technical systems, so that the public can freely discuss some hot issues online. In terms of publications, the Heritage Foundation has also made numerous achievements. The main publications include the Policy Review (quarterly), some bulletins and briefings etc.
As for the influence on the Policy Stream, as a strong supporter of the republican party, the Heritage Foundation has maintained close ties with party leaders, members of congress, and top government officials. The Heritage Foundation is especially good at promoting policy ideas through congress, which is also related to its geographical location. Its headquarters are adjacent to the Capitol hill, and its top leaders often have dinner with members of congress and government officials. And the Heritage Foundation is particularly good at producing timely, credible policy briefings, which are delivered to congress or congressional staff aides at the right time, to attract policymakers' attention in a "short and quick" manner.
Above, through the in-depth analysis of the Brookings Institution, the RAND Corporation and the Heritage Foundation three most representative American think tanks, their influence can be seen on public policy, which have been completely covered the relevant content of the Multiple-Streams Approach, and each has the emphasis, each has the characteristic.

Conclusion
As an important think-tank power, American think tanks have a significant influence on its public policies, especially at the front-end of the policy making process. The role of think tanks in promoting and guiding the issues and alternatives in the process of agenda setting cannot be underestimated. With the analysis of the classic public policy theory of "Multiple-Streams", this paper build a framework of impact mechanism for policy agenda setting with think tanks play the main role. In this process, think tanks mainly influence the Problem Stream through media publicity and public opinion, influence the Policy Stream through their own research ability and reputation influence, and influence the Political Stream through personnel exchanges with the core departments of the government. Based on the classification of American think tanks, this paper selected the typical representatives of the three types of think tanks to conduct a deeper analysis of their positioning in the Multiple-Streams framework and their influence patterns in the three types of streams. It is worth emphasizing that these three kinds of streams are bound to be more or less connected in the real society. Therefore, the ways and channels in which the think tank exerts its influence are bound to be interwoven. The division in this paper only aims to make the analytical thinking more clear and the logical chain more complete. In a word, the existence of think tanks make the process of formulating public policies in US more scientific and rational. The interaction of various subjects finally promote the improvement of policy level and the good governance of society, which is also the aspects for think tanks in other countries to learn from.