Demand for Housing

A decrease in demand for houses means that the demand curve shifts leftward, leading to a decrease in both the price of houses and the quantity of houses that are produced and sold. Shifts in a Curve versus Movements along a Curve Understanding the distinction between moving along a curve (either supply or demand) and shifting the curve is the hardest part about learning to use the supply-and-demand framework. Journalists and others frequently get confused about this—and no wonder, for it requires practice to learn how to use supply and demand properly. First, consider the market demand curve. As the price of houses increases, the quantity demanded will decrease. This is a movement along the market demand curve. Changes in anything else—anything other than price—that affects the quantity demanded appears as a shift in the market demand curve. That is, at each given price, the quantity demanded changes. Analogously, as the price of houses increases, the quantity supplied will increase. This is a movement along the market supply curve. If a change in anything else leads to a change in the quantity supplied, this appears as a shift in the market supply curve. That is, at each given price, the quantity supplied changes. Comparative Statics The example that we just discussed is an illustration of a general technique used by economists for two purposes. First, we use it to explain changes in prices and quantities that we have observed in the past. Second, we use it to predict what will happen to market prices and quantities in the future. The technique is called comparative statics. Toolkit: Section 16.8 “Comparative Statics” Comparative statics is a technique that allows us to describe how market equilibrium prices and quantities depend on exogenous events. As such, much of economics consists of exercises in comparative statics. In a comparative statics exercise, you must do the following:

1. Begin at an equilibrium point where the quantity supplied equals the quantity demanded. 2. Based on a description of an event, determine whether the change in the exogenous factor

shifts the market supply curve or the market demand curve. 3. Determine the direction of this shift. 4. After shifting the curve, find the new equilibrium point. 5. Compare the new and old equilibrium points to predict how the exogenous event affects

the market.

The most difficult part of a comparative statics exercise is to determine, from a description of the economic problem, whether it is the supply or demand curve (or both) that shifts. Once you conquer the economics of determining which curve is shifting, then it is a matter of mechanically using the framework to find the new equilibrium. A comparison of the old and new equilibrium points allows you to predict what will happen to equilibrium prices and quantities following an exogenous change.