4  BIS central bankers’ speeches
Movements in certain types of input costs, particularly changes in the price of imported goods, also can cause core inflation to deviate noticeably from its trend, sometimes by a marked amount from year to year. 17 Finally, a nontrivial fraction of the quarter-to-quarter, and even the year-to-year, variability of inflation is attributable to idiosyncratic and often unpredictable shocks.