Coordinating Manipulation In Real-time Interactive Mechanism Of College Admission And The Policy Analysis

Chinese college admission mechanism is one of the important national talent selection methods,which has been attracted widespread attention for several decades.The real-time interactive mechanism(RIM)is considered as a new direction for the future college admission reform by many scholars due to its perfect information and better performance in the fairness and efficiency of the admission results.Absolutely,if each student can report their true preferences,this mechanism can achieve the only equilibrium result under the complete information game.But in real life,rational students can mislead others to maximize their utilities,where students may coordinate to manipulate this mechanism.A high-score student can perform a last-minute change on the university applied,opening a slot for a student with a much lower score.Obviously,this manipulation will damage social welfare and fairness of admission results.Therefore,this paper will take this as an entry point,conducting a comprehensive study of this manipulation in order that Educational Examination Center can propose corresponding countermeasures to solve this problem.Based on the method of game theory,this paper models and simulates this manipulation behavior under the real-time interactive mechanism by using the agent-based simulations,in which we make the process of students submitting applications to schools as a match,where students and schools have strict preferences for both parties.As rational agents,each student would pursue maximum utility for themselves.In the model,the manipulation students will “hold” a seat by misreporting their preferences and “releasing” the seat at the optimal time where they can have maximum utilities.For the non-manipulation students they will always report true preferences.When the matching process is finished,we can evaluate the mechanism by the index of social welfare and fairness.This paper studies the reasons for this manipulation and discusses its harm and the policies to solve this problem,the basic conclusions are as follows:(1)For studying the reason of the manipulation,we calculated and compared the average utilities of manipulation students and non-manipulation students.We find that when the number of students to manipulate in a group is small,the expected utilities of manipulation students will be larger than that of non-manipulation students,which will drive more students to learn to adopt the manipulation strategy for higher utility.When the number of students to manipulate is large,the expected utilities of manipulation students begin to be lower than the utilities of non-manipulation students.Manipulation students will no longer coordinate,and then the number of manipulation students begin to decrease.In this game environment,if the expected utility from manipulation is larger than that from non-manipulation,more students will choose manipulation,otherwise,more students will adapt to non-manipulation.Then,a steady state where the manipulation students and non-manipulation students obtain the same utilities characterized the outcome of the manipulation game.At the steady state,the percentage of the manipulation and non-manipulation students will not change despite that the self-interested students are free to make their choices.Based on simulations,the social welfare and fairness of the matching are both damaged under real-time interactive mechanism due to the manipulation behaviors.(2)Because the manipulation will damage the social welfare and fairness,this paper studies that whether the multistage policy(MS-RIM)being implemented in Inner Mongolia can effectively solve this problem.With agent-based simulations,we find that students have stronger incentive to coordinate under MS-RIM.And when the mechanism executes with a small stage number,more students successfully conduct coordinating manipulation than one-stage RIM,and the social welfare and fairness are diminished;under MS-RIM with a large stage number,there are fewer successful manipulation students than one-stage RIM,and the social welfare and fairness are improved.However,a large number of stages imply that the mechanism needs to be executed for a very long time that may bring inconvenience.So this multistage policy does not really solve the problem of manipulation.(3)In order to fundamentally solve the problem of manipulation,this paper proposes two solutions,one is that making schools into different groups and restricting students' access to the schools in different groups.This method can have positive effects to solve this problem but not completely avoid this manipulation behavior,and it will bring the execution costs at the same time,which means that there is a trade-off between benefit and cost in operation.The other is that the system does not allow students to voluntarily give up their reported preferences and only allows students whose score rankings are passively pushed out of the school's enrollment plan to modify their choices,and there is no limit to the number of times.Based on the simulations,the improved admission mechanism can completely avoid manipulation without additional costs,it can balance the operability and efficiency,and we think it is an ideal countermeasure currently.