【正文】
D model ? Case 1: 1?????? 1* ngALa has a level effect but not a growth effect Interpretation: ? endogenous long run growth rate 1. positive link with population growth 2. Macroeconomics Chapter 5 33 The basic Ramp。D model ? Assumptions 1. The labor force is the single production factor 2. Generalized CobbDouglas function without capital )()1)(()( tLatAtY L??3. The fraction of the labor force is exogenous Macroeconomics Chapter 5 29 The basic Ramp。[n+g/(1?α)] ? For CobbDouglas function ???????????????11)1/(gnssAkMacroeconomics Chapter 5 20 LongRun Economic Growth Macroeconomics Chapter 5 21 LongRun Economic Growth Macroeconomics Chapter 5 22 LongRun Economic Growth Macroeconomics Chapter 5 23 Endogenous Growth Theory ? Extend the model to explain why technological progress occurs. ? Most endogenous growth models focus on investments in research and development (Ramp。(?y/y)* = g Macroeconomics Chapter 5 17 LongRun Economic Growth ? Exogenous Technological Progress ? Steadystate growth rate with technological progress ? (?y/y) * = g/(1 ? α) ?Since 0 α 1 the steadystate growth rate of real GDP per worker, (?y/y)?, is greater than the rate of technological progress, g. Macroeconomics Chapter 5 18 LongRun Economic Growth ? Exogenous Technological Progress ? (?k/k)