11  The term premium effect also wanes over time because the size of the effect depends on the expected difference between the actual size of the balance sheet now and in the future and its normal size, where the latter is rising steadily over time, primarily as a result of the trend growth in currency.
12  See John B. Taylor (1993), “Discretion versus Policy Rules in Practice,” Carnegie-Rochester Conference Series on Public Policy, vol. 39 (December), pp. 195–214. 13  See the discussion in John B. Taylor and John C. Williams (2011), “Simple and Robust Rules for Monetary Policy,” in Benjamin M. Friedman and Michael Woodford, eds., Handbook of Monetary Economics, vol. 3B, (San Diego: North Holland), pp.