Reassuringly, as the figure shows, we also found virtually no change in employment higher up in the wage distribution even up to the highest wage level. This last point is important. When you don’t see this picture, it should give you pause because it suggests that wage and job dynamics may be quite different in the control group.

The University of Washington findings show pervasive gains in employment between $20 and $39, so the cumulative job loss gets smaller at higher thresholds. For every two jobs lost under $19, one new job was created between $20 and $39. Had the authors looked at wages above $39, it’s possible that this pattern would have continued, further diminishing the lost job count. This affects how we evaluate the policy’s overall impact. For example, if you look only under $19, it suggests low-wage workers’ total quarterly earnings slipped by $39 million. But adding up changes up to $39 an hour suggests earnings rose by $17 million.

This upper-wage job growth raises concerns about the reliability of the control group because (as the authors themselves argue) minimum wages cannot plausibly affect jobs in this range. An alternative explanation for the study’s findings is that underlying fast wage growth in Seattle — and not the minimum wage itself — explains both the reduction in low-wage jobs and the gains in higher-wage jobs.

When I asked the Washington study’s authors whether this alternative hypothesis could explain the pattern of their findings, they noted a key element of timing: “We see very distinct job losses occurring exactly at the beginning of 2016,” when the minimum wage rose from $11 to $13. (The authors found job losses were much smaller at the $11 minimum wage.)

But a quick look at the data suggests something else may be going on. Between the second quarters of 2014 and 2016, earnings in Seattle grew by an incredible 21 percent, as opposed to 6 percent in parts of Washington outside the Seattle area. And the first quarter of 2016 was exactly when the very large gap in overall wage growth between Seattle and rest of the state (where the control group comes from) really opened up, coinciding with the timing of the job loss found by the University of Washington team. At this point we don’t know enough, but clearly there are some missing pieces to this puzzle.