宏观经济学介绍三

Capital goods
PPF1
Consumer goods
Capital goods
B A
Short-term aggregate demand factors can move an economy closer towards capacity (actual growth)
PPF1
Consumer goods
Price level
AS
Initially, changes in C,I,G,X,M can cause an outward shift of AD resulting in higher levels of national income (O=E=Y)
AD2(C+I+G+X-M) AD1(C+I+G+X-M)
Topic A Lecture 3 of 4
The increase in the output of goods and services in an economy over a given period of time




Economic growth is measured through changes in the level of real GDP We should however distinguish between actual growth and potential growth Short-term changes in actual growth result from changes in the components of national income (C,I,G,X,M) Long-term changes in potential growth result from changes in supply-side factors such as improvements in technology or labour productivity
AD2(C+I+G+X-M) AD1(C+I+G+X-M)
O
National output


The production possibility frontier (PPF) is a curve that shows the combinations of goods that can be produced in an economy The PPF therefore represents the maximum output level at a given moment
Capital goods
Long-term increases in aggregate supply factors can increase the amount that an economy can produce (potential growth) B A
PPF1 PPF2Fra Baidu bibliotek
Consumer goods
O
National output
Price level
LRAS
Eventually however factors of production reach capacity and so long-run aggregate supply can be represented by a vertical line, showing that increases in AD are ineffective in raising national income
National income
Trend output
Actual output
O
Time
AD2(C+I+G+X-M) AD1(C+I+G+X-M)
O
National output
Price level
LRAS1 LRAS2
If however there is an outward shift of the LRAS curve (as a result of an increase of supply-side factors) then national income increases (economic growth)



In reality economic growth rates over time are seldom steady, instead they often follow a pattern of recession, recovery and boom; during periods of recession the growth rate will fall below the trend and during boom times it will be above the trend Although there are fluctuations over the short-term it is useful to look at the long-term trend which in nearly all cases is upward; whilst the upward trend can look small even a modest growth rate compounded over time generates a large increase in living standards For example the US economy grew by an average of 1.83% from 1870 to 2006; this resulted in an increase in real GDP per capita from $3,752 to $44,260 (at 2006 prices)