15 increases in the world price of oil, which made economists more aware of the importance of shocks to aggregate supply.
4
The relationship we discussed above is a phenomenon in the short-run.
But in the long run, since unemployment always returns to its natural rate, there is no such trade-off. The non-accelerating rate of unemployment (NAIRU) is sometimes referred as along- run Philips curve. NAIRU is the specific level of unemployment that exists in an economy that does not cause inflation to increase. It often represents an equilibrium between the state of the economy and the labor market 4
Mankiw. N. G,
Macroeconomics, chapter 13 pp 380 5
http://www.investopedia.com/terms/n/non-accelerating-rate-unemploy ment.asp accessed date 01.03.2014