高宏Chapter4A概论.ppt

Chapter 4 Real-Business-Cycle Theory 周泳宏 tzhouyhjnu@jnu.edu.cn Part A 4.1 Introduction Modern economies undergo significant short-run variations in aggregate output and employment However, fluctuations do not exhibit any simple regular or cyclical pattern Kitchin’s 3-year Juglar’s 10-year Kuznets’s 20-year Kondratiev’s 50-year Some facts Some facts Some facts Okun’s Law ：US Some facts: China’s growth 经济学（季刊），4（2），P480 经济学（季刊），4（2），P480 4.2 Theories of Fluctuatios Real-business-cycle theorists Focusing on real shocks impinging on a Walrasian economy Keynesians theories Focusing on nominal disturbances affecting an economy Chapter 4 Whether aggregate fluctuations can be understood using a Valrasian model? Valrasian model A competitive model without any externalities, asymmetric information, missing markets, or other imperfections The Ramsey model is the natural Valrasian baseline model of the aggregate economy Chapter 4 Extends a variant of the Ramsey model to incorporate aggregate fluctuations A source of disturbances RBC model Shocks to the economy’s technology (production function) Government purchases Variations in employment Households’ utility depend not just on their consumption but also on the amount they work Add non-Walrasian ingredients to RBC Chapter 5-6 The technology shocks and the propagation mechanisms of real-business-cycle models are of little relevance to actual fluctuations Nominal disturbances and a failure of nominal prices and wages to adjust fully to those disturbances are central to fluctuations Chapter 5 Takes nominal stickiness as given and investigates its effects Chapter 6 Tackles the question of why nominal prices might not respond fully to disturbances 4.3 A baseline Real-Business-Cycle Model A discrete-time variation of the Ramsey model Labor and capital are paid their marginal products Real wage Real interest rate The representative household maximizes the value of U For simplicity Shocks 4.4 Household Behavior （1）Inter