Most data indicate relatively little acceleration in wage growth overall, but as I have noted the Current Population Survey shows more rapid wage growth at middle and especially the bottom end of the wage distribution over the last three years. The "Workforce Vitality Index" produced by ADP, shows a similar picture.

Its most recent survey shows hourly wage growth of more than 6.0 percent for workers earning less than $20,000 a year and 5.6 percent for workers earning $20,000 to $50,000 a year. This compares to increases of 5.4 percent and 5.0 percent in the 3rd quarter of 2014, the first period in the sample. By comparison, wages increased 3.4 percent on the most recent quarter for workers earning more than $75,000 a year, virtually the same as the 3.3 percent increase in the 3rd quarter of 2014. (These are figures for job holders — found on page 5.)

This supports the view that the tightening of the labor market has disproportionately benefited those at the bottom end of the wage distribution. It also should be a warning of bad effects if the Fed moves too aggressively in raising interest rates and causes the unemployment rate to rise.