Introduction x What are the three big problems macroeconomics studies? 兴GDP Calculation intermediate: inventories used: GNP Real v.s. Nominal(deflator; CPD) 兴 Okun's lawIntroduction What are the three big problems macroeconomics studies? GDP -- Calculation: intermediate;inventories;used;GNP -- Real v.s. Nominal (deflator; CPI) Okun’s Law