A hidden gauge of the jobs market is approaching historic lows — and it reveals the most underrated

The April jobs report showed that the unemployment rate fell to a new 17-year low of 3.9%.  A less obvious metric — the gap between this rate and the underemployment rate that includes discouraged workers — has also been shrinking since the financial crisis.  It backs up claims by several companies that skilled workers are more expensive and harder to find, according to Tobias Levkovich, Citi's chief US equity strategist.  It also signals that wage inflation will continue rising, Levkovich...