The Federal Reserve is setting out to do something it has never accomplished before: reduce inflation a lot without significantly raising unemployment.

Central bank officials think it is possible with calibrated interest rate increases that slow booming demand just enough to take steam out of an overheated economy. But even one of the Fed’s closest allies, U.S. Treasury Secretary Janet Yellen, sees the risk of failure. “It will require skill and also good luck,” the former Fed chair said in public comments in Washington last week.