Michael Greenstone and Adam Looney of the Brookings Institution, a Washington think tank, did some rough calculations estimating the job growth needed to reduce the unemployment rate, 7.7 percent in November, to 6.5 percent. Their conclusion: If job creation’s modest pace, about 220,000 a month during the past year, continues, the Fed’s mid-2015 prediction will be fulfilled.

But of course, it may not continue. Greenstone and Looney also estimated what would happen under different rates of job growth, as the numbers below show. The first number represents average monthly job growth; the second shows when the country would hit 6.5 percent unemployment under such a scenario.

150,000 — Spring 2018
200,000 — Fall 2015
250,000 — End of 2014
300,000 — Spring 2014