Ms. Yellen has been a powerful force in the Fed during the deep recession and sluggish recovery. She has argued for the central bank to provide more clarity to market participants and supported its campaign to soak up trillions of dollars of Treasury and mortgage-backed debt in order to bring down interest rates and spur investors to start spending.

She has also publicly expressed concern over the problems in the American labor market. In particular, she has focused on the persistent high rate of long-term joblessness — which might scar the unemployed even after they find a job, depressing their earnings and even their children’s earnings down the road.

The employment crisis “has imposed huge burdens on all too many American households and represents a substantial social cost,” Ms. Yellen warned in a major speech last year. “If these jobless workers were to become less employable, the natural rate of unemployment might rise,” meaning a higher jobless rate and a less vibrant economy even during good economic times.

Her views have prompted speculation among market participants that Ms. Yellen — long considered a contender for the top position at the Fed — might be a stronger proponent for the Fed’s extraordinary policies than Mr. Bernanke.

But their views have not differed all that much.

In December, Ms. Yellen joined Mr. Bernanke in supporting the Fed’s decision to start tapering its purchases of Treasury and mortgage-backed debt to a pace of $75 billion a month from $85 billion a month. The decision came as new data showed stronger economic growth and a significant drop in the unemployment rate, to 7 percent in November from 7.8 percent a year before.

The Fed’s decision “to modestly reduce the pace of asset purchases at its December meeting did not indicate any diminution of its commitment to maintain a highly accommodative monetary policy for as long as needed,” Mr. Bernanke said in a speech this month, reflecting on his tenure. “It reflected the progress we have made toward our goal of substantial improvement in the labor market outlook.”

The strategic shift will likely dominate the early part of Ms. Yellen’s tenure, which is expected to start on Feb. 1. Fed watchers have warned that withdrawing support from the economy comes with significant risks. Pull back too soon and the economy could face subpar growth; Wait too long and the markets could overheat.