Gene Epstein of Barron’s explains in his latest column why inflation might be heading toward the targets the Federal Reserve has been watching.

Might there be a light at the end of the inflationary tunnel, signaling to the Federal Open Market Committee that inflation could soon be running near its target of 2%? The consumer price index for October, released last week, should have encouraged Yellen & Co. to expect that by January, 12-month gains on the CPI could indeed be running close to 2%.

In fact, actual inflation of 2% is not specifically required for an interest-rate hike. As the hawkishly tilted press release from the FOMC’s Oct. 28 meeting made clear, all that’s needed to trigger higher interest rates is that the committee be “reasonably confident that inflation will move back to its 2% objective over the medium term.”

You wouldn’t think that the October reading provided much cause for such confidence. The percentage gain on the headline index over 12 months—the FOMC’s chosen interval for tracking inflation—ran at just 0.2% through October, up from 0% in September. At that pace, it would take until next summer for the 2% goal to be realized.

BUT THE ARITHMETIC OF the consumer price index’s components suggests that this January is more likely. Arithmetically separate the index into two parts: the energy component, and the all-items component, excluding energy. The energy reading then reveals itself as the swing factor.

The 12-month change in the all-items pace of inflation, excluding energy, ran at 1.9% through October. And so far this year, the 12-month change has been fluctuating in a narrow range between 1.7% and 1.9%. …

… RICHMOND FEDERAL RESERVE President Jeffrey Lacker, a hawk on raising short-term interest rates, has referred to “persistently strong consumption growth” as a key reason for his stance.

Lacker’s remark was questioned in light of what seemed to be weak retail spending in October. But the broad numbers bear him out. From the fourth quarter of 2014 through the third quarter of 2015, four-quarter growth in real consumer spending has consistently run at cyclical highs of 3.2% to 3.3%.