my country is in the stage of reform and the key period of development。In the process of working hard to realize the transformation of economic growth and optimization of industrial structure，An important task is the various policies issued by the country and localities，Especially the economic policy is correctly evaluated，To find a problem、Summary experience，Filter the policy in time，Provides reference for formulating new policies and supporting measures。Policy Evaluation Merit Economics，It combines the ideas of natural experiments with the structural model，Statistical inference method of estimating various causal effects through development identification，Provides methodology support for the effectiveness and advantages and disadvantages of scientific evaluation policies。

High complexity of the economic system、Self -selection behavior of limited rational individuals and limitations that can obtain data，Make the impact of evaluating a policy or a major event is not as easy as it looks like。The difficulty of using a large -capacity micro data assessment is mainly the following three aspects。

First，Data missing question。Assuming that the government is preparing to implement a policy to encourage enterprises to increase productivity through technology upgrades。If the productivity Y0 and the productivity Y1 after the implementation of the policy before the implementation of the policy can be observed at the same time，Then the difference between the two undoubtedly measures the net effect of the policy on the company。but，In reality, we can generally only observe the results of the individual in the real state，that is y = DY1+(1-DY0)，Where D = 1 means that the individual participates in the policy，d = 0 means that the individual does not participate in Bet365 lotto review the policy。This means that the policy effect of a single enterprise cannot be recognized。The above problems are called the fundamental problem of policy assessment。To overcome it，Economists need to be under certain assumptions，Using known data predicting individuals who appear in the unknown state of anti -facts。

Second，interference problem of confusion factor。Among the many issues of policy evaluation，​​Simply make the results of the results before and after the incident，The estimation of the estimation often mixes the effects of other interference factors outside the policy effect。For example，It is necessary to evaluate the stimulating role of a major economic stimulus policy on a major economic stimulus policy on the GDP of a certain area。Simply reduce the value obtained after the region's GDP before and after the implementation of the policy，At least the role of the following three factors: First, the role of the major economic stimulus policy on GDP; the other is that it occurs at the same time as the major policy，The impact of other small and medium -sized policies on the economy; third, even if there is no economic policy，Natural economic growth in the area。In order to peel off the net effect of research policies to study from various mixed factors，Methods commonly used in measurement economics are the tendency score matching method (Propensity Score Matching, PSM) and dual differential method, DID)。

third，Unbelled individual heterogeneity。This is one of the basic features of micro data。In policy assessment，Unsure that heterogeneity mainly brings two problems。First，Personal when deciding whether to participate in the policy，Unobstructed personal preferences and rational expectations for policy consequences are related to the disturbance items in the result equation，As a result, policy is no longer a natural test，Therefore, it has endogenous。This kind of endogenous caused by an observed variable cannot be eliminated by PSM，Intervention of bet365 best casino games tool variables often needs。This brings difficulty in identifying and estimated policy effects。Next，More and more economists discovered，Even if all observation variables are controlled，The impact of policy on individuals still vary from person to person。In recent years，Merit economist began to turn to the identification and estimation of policy distribution/division number processing effect，This trend reflects the attention and attention of the unspeakable heterogeneity in policy assessment。

Data lack and other problems lead to the policy effect that generally cannot be recognized at the individual level。The parameters of the common measurement policy effect include the average processing effect, ATE)，It is the expectation value of the individual treatment effect on the entire crowd，reflect the average value of the policy effect on everyone。otherwise，There is also the average effect of the processing group., atet)，It is the expectation of individual treatment effects in the processing group crowd，reflects the average value of the policy effect in the part of the individual。Whether ATE or ATET，Their common features are the average effect of a solid portrayal policy with a single parameter to a single parameter.。

In recent years，Researchers when using the processing effect model to evaluate economic policy，Pay more and more attention to analyzing the policy of the division processing effect (Quantile Treatment Effect, QTE) and distributed processing effects, DTE)，instead of focusing on ATE。This trend appears，On the one hand, the degree of influence of policy on the end of the end of the variable distribution is often different from the impact on the middle section of the variable distribution; on the other hand,，Many related social benefits、The answers to equality questions depend on the distribution of researchers to understand the policy effects in the entire audience。Taking the university expansion policy implemented by China in 1999 as an example。bet365 Play online games In just a few years，China's higher education quickly transitioned from elite education to the era of mass education。At present, China's higher education gross enrollment rate reaches 40%，The annual enrollment scale of ordinary colleges and universities exceeds the 7 million mark，Living in the world first。for a long time，One of the focus of discussion on the expansion of higher education is whether the expansion policy really helps reduce income inequality，Promoting social fairness。If you only estimate the change of educational returns caused by the university's enrollment，So at best, you can only understand that this policy increases the average salary of people，But it is difficult to know how the policy affects people's salary distribution，Therefore, it is impossible to answer questions about income inequality。In order to answer questions about income inequality，It can be estimated that QTE/DTE in different periods can be implemented by the expansion policy，Help understand the heterogeneity impact caused by policies。

Use PSM recognition policy effects to depend on strong conditions for external hypothesis。Conditional exogenous means that a set of observable variables have been controlled after，d and (y1，y0) Independent situation。In actual，When the individual determines the value of D，Its decision -making process depends on some researchers that cannot be observed，Including personal ability、Factors such as endowment and risk preferences。At the same time, these factors are influenced in turn (y1，Y0）。For example，In the process of studying the role of higher education on higher education on personal wages，d = 1 indicates that I studied university，d = 0 means university。Unbelled personal abilities determine whether this person can enter university through academic performance。At the same time，Personal ability is also closely related to its performance in the labor market。In this case，Even if you control the observed individual bet365 Play online games characteristics，d and (y1，y0) Still related。At this time, the intervention of tool variables is required to consistently estimate the net effect of college for wages。

After the implementation of a policy，Although it can be observed at the same time, changes before and after the processing group，But this change also contains the change of policy processing effect and unbelievable time trends。If the time trend of the time trend is the same and the control group is the same，So you can take two differential methods，Remove the common time trend out，to obtain an estimated value of the average processing effect。This is the idea of ​​the DID method。DID's main advantage is that it is easy to calculate，You can accept a selective error，But the main problem is，The hypothesis that must maintain the same time trend between the processing group and the control group is sometimes not in line with reality，It is difficult to test。

When the probability of accepting policy influence becomes a non -continuous function，Retomment Discontinuity Design, RDD) has become a very popular method for the processing effect of the "quasi -experiment" policy processing effect in recent years。3860_3881，Economists usually use accurate breakpoint regression (Sharp RDD)。3844_3865，When it is affected by some unbelievable selection variables when receiving the processing effect,，Generally use fuzzy breakpoint regression (fuzzy RDD)，This is an estimated method similar to the two -step method variables for processing tool variables。

In recent years，Micro -measurement economics has achieved rapid development in policy evaluation。Due to the advent of the era of big data，This field also faces more development opportunities and challenges。Policy evaluation in the background of big data is not only the frontier of economic academic development，and can meet the major needs of national development。Generally speaking，The future development direction of this field may include bet365 live casino games the following aspects。

First，The Nobel Prize winner James Heckman (James Heckman)，At the same time, it is also the leader of policy evaluation of the development of economics，The three major tasks of the micro -measurement evaluation of policy intervention have been explicitly proposed: first, the effect of evaluating the implementation of the policy; the other is to predict that the policy has been implemented in the new environment、The effects to be produced in the new crowd; the third is the effect that the new policy that has not yet been implemented will be produced in the new environment。Most of the research on policy assessment only pays attention to the first point。In view of policy makers often need to find problems in practice、Summary experience、Make fine -tuning policies，and formulate new policies and related supporting measures，The above second、Three tasks will be one of the key development directions in this field。

Second，Pay more attention to the identification of the effect of heterogeneous policy、Estimation and inference。Parameters that can reflect the heterogeneity that can reflect the effect of the policy include the division processing effect and the distribution processing effect。Actually，Subject number processing effect can also be divided into conditional division processing effects and unconditional division processing effects，The two are close to the name，But the steps of recognition and estimation go far。Another，Although the DID method has become one of the common methods of policy assessment，But the research using this method basically only pays attention to the recognition and estimate of ATE type parameters。How to reflect the heterogeneity effect of the policy in the DID model and identify it，will be a question worth studying。

third，At present, most of the processing effect models present the following features: only applicable to single -section data，or two phases of data (such as DID); policy variables are mostly 0/1 value variables。Extend the results to the use bet365 live casino games of multi -phase panel data for policy assessment、Evaluation of policy variables of continuous value，and dynamic processing effect model will be the direction that can be studied in the future。Dynamic processing effect model refers to the implementation of a policy in two stages，People can freely choose whether to continue to participate in the next stage of the policy，At this time, the results of the first stage will affect whether individuals participating in the second stage decision。

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