are real and well described in the paper. that said, i am not convinced that this distinction has played a central role in determining the successes and challenges of fomc communications in this remarkable era, or that it helps us improve in the future. the authors are, in their words, “ unabashedly judgmental ” in labeling specific communications to be either time - or data - based. 2 my own judgments differ in significant respects from those described in the paper. see michael feroli, david greenlaw, peter hooper, frederic mishkin, and amir sufi ( 2016 ), “ language after liftoff : fed communication away from the zero lower bound, ” paper presented at the 2016 u. s. monetary policy forum, a conference sponsored by the university of chicago booth school of business, held in new york, february 26 ; see https : / / research. chicagobooth. edu / igm / events / conferences / 2016usmonetaryforum. aspx. see feroli and others, “ language after liftoff, ” in note 1, p. 20 bis central bankers ’ speeches discussion of forward guidance i will start in december 2008, when the committee said that “ weak economic conditions are likely to warrant exceptionally low levels of the federal funds rate for some time. ” 3 this relatively weak time - based guidance was strengthened in a series of steps until august 2011, when the time - based language became “ at least through mid - 2013. ” 4 the calendar reference was later extended in a couple of steps to “ at least through mid - 2015. ” 5 this guidance was explicitly time - based, and the authors seem to agree that, through this point, the guidance served its intended purpose at the zero lower bound by pushing down medium - and longer - term rates. 6 at the december 2012 meeting, the committee ended this calendar - based guidance. the committee instead adopted thresholds, saying that it did not intend to raise rates at least as long as unemployment remained above 6 - 1 / 2 percent, inflation one to two years ahead was projected to be no higher than 2 - 1 / 2 percent, and longer - term inflation expectations remained well anchored. 7 the adoption of thresholds was a clear change to data - based guidance, as its principal sponsors had frequently urged. 8 the point was not to provide additional stimulus at the time of adoption, but rather to allow market participants to adjust their expectations about future monetary policy in response to incoming

. let ’ s turn briefly to 2015 and the run - up to last december ’ s increase in the federal funds rate – also an important focus of the paper. the authors and many market participants are critical of communication around the september meeting. with the june 2015 summary of economic projections ( sep ) showing that 15 of 17 fomc participants judged that appropriate policy would entail an initial increase in the federal funds rate by the end of 2015, markets saw about a 50 percent chance that the first increase would occur in september. this probability fell to about 30 percent after global markets experienced a sudden bout of volatility following china ’ s surprise devaluation of its currency in august. at the september meeting, the fomc decided to wait to see how global markets and the economy evolved, noting in its statement that “ recent global economic and financial developments may restrain economic activity somewhat and are likely to put further downward pressure on inflation in the near term. ” 13 a data - driven committee, making decisions meeting by meeting, is likely to surprise markets from time to time. the authors join many others in criticizing the “ measured pace ” period of 2004 through 2006, during which the committee increased rates by 25 basis points at 17 consecutive fomc meetings. a common criticism has been that this high level of predictability made investors complacent, encouraging a buildup of leverage and helping set the stage for the global financial crisis. that criticism may well overstate the importance of the committee ’ s communications ; nonetheless, a number of fomc participants have said that the committee intends to be “ data driven ” and not fall into an excessively predictable, datainsensitive path. lower predictability implies more surprises. in the statement released after its october 2015 meeting, the committee reemphasized data dependence and focused on the importance of incoming data for the committee ’ s decision “ at its next meeting, ” which led the market to increase its estimated probability of a december rate and employ its other policy tools as appropriate, until such improvement is achieved in a context of price stability. in determining the size, pace, and composition of its asset purchases, the committee will, as always, take appropriate account of the likely efficacy and costs of such purchases. ” ( board of governors of the federal reserve system ( 2012 ), “ federal reserve issues fomc statement, ” press release, december 12, paragraph 4. ) ben s. bernanke ( 2015 ), the courage to