Standard wage data show that between the spring of 2017 and the spring of 2018, real wages in the U.S. increased only 0.1%. But there are three major problems with these data. First, they don’t account for fringe benefits, which are an increasing proportion of employee pay. Second, standard wage data use an index that overstates the inflation rate. Third, each year the composition of the workforce changes, as older, higher-paid workers retire and young, lower-paid workers enter the workforce.

A study released this month by...