Wages in the United States are going up, but their growth is shrinking, says Glassdoor chief economist Andrew Chamberlain.

Expand chart Reproduced from Glassdoor Local Pay Reports; Chart: Axios Visuals

By the numbers: Wages should be rising an average of 3%–4% given the tightness of the job market, Chamberlain says.

According to official data from the U.S. Bureau of Labor Statistics, wage growth was a lower 2.6% in February.

from the U.S. Bureau of Labor Statistics, wage growth was a lower 2.6% in February. Yes, but: Glassdoor data — based on a survey of 100,000 salaries posted by the jobs site every month — show even lower growth, shrinking to just 1% last month.

The bottom line: Chamberlain attributes the stagnation to poor growth in productivity. If worker productivity is rising as measured by what's made each hour, ordinarily wages should rise because they can charge more for their labor. But hourly productivity is not rising, hence neither are their wages. “I don’t think anyone has an answer for that,” he said.