## Aggregate Demand and Aggregate Supply

This chapter introduces the Aggregate Demand/Aggregate Supply model of macroeconomics. Read the introduction and Section 1 to learn about Aggregate Demand and the three effects (weath, interest rate, and international trade) that cause the downward slope. Recall the difference between quantity demanded and demand - the same logic applies to Aggregate Demand. Identify the variables that change (shift) the Aggregate Demand curve. Read this chapter and attempt the "Try It" exercises. You will revisit certain sections of the chapter later in this unit.

### Aggregate Demand

#### Case in Point: The Multiplied Economic Impact of SARS on China's Economy

Severe Acute Respiratory Syndrome (SARS), an atypical pneumonia-like disease, broke onto the world scene in late 2002. In March 2003, the World Health Organization (WHO) issued its first worldwide alert and a month later its first travel advisory, which recommended that travelers avoid Hong Kong and the southern province of China, Guangdong. Over the next few months, additional travel advisories were issued for other parts of China, Taiwan, and briefly for Toronto, Canada. By the end of June, all WHO travel advisories had been removed.

To estimate the overall impact of SARS on the Chinese economy in 2003, economists Wen Hai, Zhong Zhao, and Jian Want of Peking University's China Center for Economic Research conducted a survey of Beijing's tourism industry in April 2003. Based on findings from the Beijing area, they projected the tourism sector of China as a whole would lose $16.8 billion – of which$10.8 billion came from an approximate 50% reduction in foreign tourist revenue and $6 billion from curtailed domestic tourism, as holiday celebrations were cancelled and domestic travel restrictions imposed. To figure out the total impact of SARS on China's economy, they argued that the multiplier for tourism revenue in China is between 2 and 3. Since the SARS outbreak only began to have a major economic impact after March, they assumed a smaller multiplier of 1.5 for all of 2003. They thus predicted that the Chinese economy would be$25.3 billion smaller in 2003 as a result of SARS.