Federal Rserve Bank of San Francisco comments: Since 2007, Federal Open Market Committee participants have been persistently too optimistic about future U.S. economic growth. Real GDP growth forecasts have typically started high, but then are revised down over time as the incoming data continue to disappoint. Possible explanations for this pattern include missed warning signals about the buildup of imbalances before the crisis, overestimation of the efficacy of monetary policy of following a balance-sheet recession, and the natural tendency of forecasters to extrapolate from recent data. .
Economic forecasting can be a humbling endeavor. In a cross-country study of private-sector forecasts from 1989 to 1998, Loungani (2001) finds that “the record of failure to predict recessions is virtually unblemished.” He also finds that forecast revisions in one direction tend to be followed by further revisions in the same direction and that one-year-ahead growth forecasts are typically too optimistic. An updated study by Ahir and Loungani (2014) finds that the private-sector’s record of failure to predict recessions remained intact through 2008 and 2009. A study by Alessi, et al. (2014) finds that one-year-ahead growth forecasts from the Federal Reserve Bank of New York and the European Central Bank from 2008 to 2012 exhibited substantial overoptimism, averaging 1.6 to 2.4 percentage points above actual growth. The SEP growth forecasts fit the pattern of these various studies.Research shows that people tend to use simple forecast rules that extrapolate from recent data (Williams 2013).
Research has identified numerous instances of persistent bias in the track records of professional forecasters. These findings apply not only to forecasts of growth, but also of inflation and unemployment (Coibion and Gorodnichencko 2012). Overall, the evidence raises doubts about the theory of “rational expectations.” This theory, which is the dominant paradigm in macroeconomics, assumes that peoples’ forecasts exhibit no systematic bias towards optimism or pessimism. Allowing for departures from rational expectations in economic models would be a way to more accurately capture features of real-world behavior. Growth
