The two most important categories of durable goods in the National Income and Product Accounts are "motor vehicles and parts" and the other is "furniture and other household equipment." Each of these is around 40 percent of durable goods. The remaining 20 percent is included in a category marked "other."

Both of the major categories are relatively self-explanatory. The "motor vehicles and parts" entry includes any cars, trucks, motor homes, and tires purchased by the household sector. The "furniture and other household equipment" entry includes sofas, dining room tables, refrigerators, rocking chairs, microwave ovens, and television sets purchased by the household sector.

As a group, durable goods are important to the macroeconomy for two related reasons.

• One, durable goods last for several years meaning that consumers buy them infrequently. They buy cars, trucks, and other vehicles every 3-8 years. They by refrigerators, stoves, and other large kitchen appliances every 10-20 years. The same time frame applies for household furniture, as well.

• Two, durable goods are often purchased using credit or borrowed funds. Few people pay cash for a car. Most borrow the funds from banks or other lending agencies. Furniture and appliances are frequently purchased using credit cards or store installment plans. The key is that such borrowing is sensitive to interest rates. Higher interest rates increase the cost of borrowing and make the overall cost of purchasing durable goods greater.

Taken together these indicate that the purchase of durable goods is closely related to business-cycle instability. During the recovery of a business cycle, when interest rates tend to be low, consumers begin purchasing durable goods. These purchases help fuel the ensuing expansion, which adds more income to the household sector and lets consumers buy additional durable goods. However, as interest rates rise during the expansion, and with consumers now possessing most of the long-lasting durable goods that they need, expenditures on durable goods tend to fall. This can trigger, or at least compound, a business-cycle contraction.