Philip Tetlock, a professor at the University of California, Berkeley, spent two decades
tracking 82,000 predictions made by 284 experts. His findings, reported in his book, 
“Expert Political Judgment,” are that, on average, the expert's predictions were only bit
better than random guessing would have been. He writes, “It made virtually no difference
whether participants had doctorates, whether they were economists, political scientists,
journalists or historians, whether they had policy experience or access to classified
information, or whether they had logged many or few years of experience.” The only
consistent attribute was fame, and the relationship was inverse. The more famous experts
made worse predictions than the unknown forecasters did.

Dean Baker [http://www.prospect.org/csnc/blogs/beat_the_press] has often pointed out that
the media, when reporting on a forecast made by a prominent economist, should (but never
does) qualify the prediction with a list of previous predictions made by the expert that were either
right or wrong.

But economists, even when their predictions are right, have a way of basing their predictions on
sheer nonsense.