More than half the gauges Janet Yellen uses to track the U.S. labor market are below pre-recession levels, reinforcing the likelihood she will support an easier-for-longer Federal Reserve policy as she prepares to succeed Ben S. Bernanke as chairman.

While payrolls have increased and firings slowed, four measures — unemployment, labor force participation and rates on hiring and voluntary quits — are still worse than at the start of the recession in December 2007. Yellen, in a speech earlier this year, named the six gauges as among those she would “consider in judging the strength of the labor market in connection with” the Fed’s asset purchase program.