May 05 2010
Facts and the Phillips Curve: new evidence of the short-run trade-off between unemployment and inflation
Introduction: The following is a selection of a chapter from my new Economics textbook project, the Pearson Baccalaureate Economics text, which will be available to IB Economics teacher for the 2011-2013 school year.
It should be noted that the original Phillips Curve theory did not distinguish between the short-run and the long-run. In fact, the original Phillips Curve itself was a long-run model demonstrating a trade-off between unemployment and changes in the wage rate over a span of 52 years in the United Kingdom.
Up until the early 1970s, the Phillips Curve was treated as a generally accurate demonstration of the relationship between two important macroeconomic indicators. Throughout the 60′s data for the United States showed in most cases that increases in unemployment corresponded with lower inflation rates, and vis versa.
As can be seen above, between almost every year of the decade a fall in the inflation rate corresponded with a rise in unemployment. The only exceptions were between 1962 and 1963, when both unemployment and inflation increased slightly, and between 1968 and 1969, when again both variables increased. Phillips' theory of the trade-off between unemployment and inflation was generally supported throughout most of the decade, as the downward slope of the line in the graph above demonstrates.
Beginning in 1970, however, data for the US began to point to a flaw in the Phillips curve theory. Throughout the decade, both unemployment and inflation rose in the US, as oil exporters in the Middle Ease, united under the Oil Producing and Exporting Countries (OPEC) cartel, placed embargoes on oil exports to the US in retaliation for America's support of Israel in a war against its Arab neighbors. The resulting supply shock in the US led to energy and petrol shortages and rising costs for US firms, forcing businesses to reduce costs by laying off workers, while simultaneously raising output prices. Several other macroeconomic variables contributed to rising unemployment and inflation in the late 1970s, including the return of tens of thousands of troops from the Vietnam War who entered the labor market and found themselves unemployed as firms reduced output in the face of rising energy costs. The Phillips Curve for the 1970s told a somewhat different story about inflation and unemployment than that of the 1960s.
Between 1973 and 1974, both the unemployment rate and the inflation rate increased significantly, and even as unemployment increased by almost 3% between 1974 and 1975, the inflation rate fell by less than 2% but still remained at nearly 10%. Unlike the 1960s, the 1970s was a decade of both high unemployment AND high inflation. By the end of the decade, unemployment was at approximately the same level as it was in 1963 (5.8%) but inflation was nearly 10 times higher (11.22% in 1979 versus just 1.24% in 1963). The Phillips Curve theory was apparently busted, as the seemingly random scattering of data in the graph above points to no discernible trade-off between unemployment and inflation throughout the 1970s.
Several prominent economists in the 1970s, including Nobel Laureate Milton Friedman, revived the classical view of the macroeconomy which held that policies aimed at managing aggregate demand would ultimately be unsuccessful at decreasing unemployment in the long-run, since a nation's output and employment would always return to the full-employment level regardless of the level of demand in the economy. Friedman, whose theory of the macroeconomy would come to be known as monetarism, believed that changes in the money supply would lead to inflation or deflation, but no change in unemployment in the long-run. Monetary policy and its effects on aggregate demand and aggregate supply will be explored in more depth in a later chapter in this book. The basic premise of the monetarists, however, was that in order to maintain stable prices and low unemployment, the nation's money supply should be allowed to grow at a steady rate, corresponding with the desired level of economic growth. Any increase in the money supply aimed at stimulating spending and aggregate demand would result in an increase in inflationary expectations, an increase in nominal wages, and a leftward shift of aggregate supply, resulting only in higher inflation and no change in real output and employment. Therefore, monetary rules were needed to assure that policymakers would not manipulate the supply of money to try and stimulate or contract the level of aggregate demand in the economy.
By the late 1970s, our current interpretation of the Phillips' theory as including both a short-run and a long-run model became widely adopted. The short-run Phillips Curve may accurately illustrate the trade-off between unemployment and inflation observed in the period of time over which wages and prices are relatively inflexible in a nation's economy. For instance, during the twelve month period between July 2008 and June 2009, the level of consumption and investment in the US fell as the economy slipped into recession. Unemployment rose and inflation decreased and eventually became negative in the final three months of the period. The graph below shows the relationship between unemployment and inflation during the onset of the recession in 2008 and 2009.
A clear trade-off appears to have existed in the twelve month period above. At the time of writing, it is yet to be seen whether the unemployment rate will return to its pre-recession level in the United States. Although in the short-run it seems likely that the downward sloping Phillips Curve holds some truth, a look at a longer period of time for the same country tells a different story. The graph below shows the unemployment / inflation relationship during the twelve years leading up to the onset of recession in 2008.
Looking at data for a longer period of time shows that even as inflation fluctuated between 0.5% and 4%, US unemployment remained in a relatively narrow range of between 4% and 6%. Year on year unemployment and inflation often increased together, while at other times demonstrated an inverse relationship as Phillips' theory predicts it should. The narrow range of unemployment portrayed in the data above is evidence that the Long-run Phillips curve for the US between 1997 and 1998 was more like a vertical line than a downward sloping one. It appears that during the period above the natural rate of unemployment for the United States was around 5%; meaning that even as AD increased and decreased in the short-run, the level unemployment remained relatively steady around the natural rate of 5% in the long-run.
The 1970′s represented a turning point in the mainstream economic analysis of the relationship between inflation and unemployment. Demand-management policies by governments may be effective at fine-tuning an economy's employment level and price level in the short-run, but as data from the 1970′s and early 2000s shows, in the long-run a nation's level of unemployment tends to be independent of the inflation rate, and is likely to remain around the natural rate of unemployment once wages and prices have adjusted to fluctuations in aggregate demand. In response to supply shocks such as the oil shortages of the 1970′s, both inflation and unemployment may increase at the same time, calling into question the validity of the original Phillips Curve relationship. Despite the breakdown in the relationship between unemployment and inflation in the long-run, the evidence from the recession of 2008 and 2009 seems to support the theory that an economy in which aggregate demand is falling will experience a short-run trade-off between the rate of inflation and the rate of unemployment.