(RECAP: The drop in the last month proved forecasters wrong, said Douglas Duncan, chief economist of Fannie Mae in Washington. After the Federal Reserve announced in December it would begin tapering purchases of mortgage-backed securities, all the major housing forecasters said rates would jump this quarter. Economists didn’t foresee that investors would react to the Fed’s retreat by moving money from emerging markets into U.S. Treasuries, driving down home-loan rates. The drop in borrowing costs means some buyers will purchase a home sooner than they had planned.)