Quantitative Aggregate Economics
介绍了一个以个体明确建模、动态前瞻决策为核心的经济学框架，用于通过计算实验评估经济政策，适合关注宏观政策量化分析的学者。
I am delighted to be able to present this lecture before so many people. I’m also very happy when I get to work with models inhabited by many people. That is the key to the framework for which Ed Prescott and I were cited by the Nobel Committee: Individuals are introduced explicitly in the models. Their decision problems are fully dynamic—they are forward looking. That is one of the prerequisites for what we ultimately seek, which is a framework we can use to evaluate economic policy. The eminent researcher and 1995 Nobel laureate in economics, Bob Lucas, from whom I have learned a great deal, wrote: “One of the functions of theoretical economics is to provide fully articulated, artificial economic systems that can serve as laboratories in which policies that would be prohibitively expensive to experiment with in actual economies can be tested out at much lower cost ... (Lucas, 1980, p. 696). Our task, as I see it ... is to write a FORTRAN program that will accept specific economic policy rules as ‘input’ and will generate as ‘output’ statistics describing the operating characteristics of time series we care about, which are predicted to result from these policies” (pp. 709–10). The desired environments to which Lucas refers would make use of information on “individual responses [that] can be documented relatively cheaply ... by means of ... censuses, panels [and] other surveys ...” (p. 710). Lucas seems to suggest that economic researchers place people in desired model environments and record how they behave under alternative policy rules. In practice, that is easier said than done. The key tool macroeconomists use is the computational experiment. With its help, the researcher performs exactly what I just described—places the model’s people in the desired environment and records their behavior. But the purpose of the computational experiment is broader than only to evaluate policy rules. The computational experiment is useful for answering a host of quantitative questions, that is, those for which we seek numerical answers. When evaluating government policy, the policy is stated in the form of a rule that specifies how the government will behave—what action to take under various contingencies—today and in the indefinite future. That is one reason it would be so difficult and prohibitively expensive to perform the alternative Lucas mentions, namely, to test the policies in actual economies.