If you go on to take more advanced courses in macroeconomics, you will likely learn about a class of models called dynamic, stochastic, general equilibrium models, often abbreviated as DSGE models. These models are dynamic because they trace the path of variables over time. They are stochastic because they incorporate the inherent randomness of economic life. They are general equilibrium because they take into account the fact that everything depends on everything else. In many ways, they are the state-of-the-art models in the analysis of short-run economic fluctuations.

The dynamic AD–AS model we have presented in this chapter is a simplified version of these DSGE models. Unlike analysts using advanced DSGE models, we have not started with the household and firm optimizing decisions that underlie macroeconomic relationships. But the macro relationships that this chapter has posited are similar to those found in more sophisticated DSGE models. The dynamic AD–AS model is a good stepping-stone between the basic model of aggregate demand and aggregate supply we saw in earlier chapters and the more complex DSGE models you might see in a more advanced course.3

The dynamic AD–AS model also yields some important lessons. It shows how various macroeconomic variables—output, inflation, and real and nominal interest rates—respond to shocks and interact with one another over time. It demonstrates that, in the design of monetary policy, central banks face a tradeoff between variability in inflation and variability in output. Finally, it suggests that central banks need to respond vigorously to inflation to prevent it from getting out of control. If you ever find yourself running a central bank, these are good lessons to keep in mind.

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