The correlation between the forward earnings yield and government bond yields was only 19% over the 1881 to 2002 period. Over the period from 1999 to 2013 the correlation was negative, with the Fed model incorrectly giving a rare "sell signal" in 2003 (turned out to be a poor signal), and a strong "buy signal" in 2007 (also turned out to be a poor signal). An academic study of international data showed that the Fed model equilibrium only shows up in 2 out of 20 evaluated international markets, with the author concluding that "evidence from 20 countries that seriously questions its empirical merits".