This has been done. Dube, Lester, Reich is a very rigorous study that compares all minimum wage increases across all state borders between 1990 and 2006. It controls for most things.
No effect on employment was found, period.
> This short-run employment response is in line with both our estimates in this paper, as well as recent work studying the restaurant industry, such as Dube, Lester, and Reich (2010), Neumark, Salas, and Wascher (2014), and Allegretto et al. (2016)
The disagreement is over the long run effects:
> We find that the short-run employment effect captures only a small share of the long-run employment effect generated in the model. ...
> much of the recent research suggesting that minimum wage hikes barely reduce the number of jobs in the short run should be taken with caution. The longer-run disemployment effects are potentially large.
So when you say "no effect was found" it's because they were only looking in the short run.
Umm... no. From the abstract:
>Our findings are robust to allowing for long-term effects of minimum wage changes
Read the paper. Seriously.
"We show that this heterogeneity is spatial in nature. We also show that in the presence of such spatial heterogeneity, the precision of the individual case study estimates is overstated. By essentially pooling all such local comparisons and allowing for spatial autocorrelation, we address the dual problems of omitted variables bias and bias in the estimated standard errors"
Based on the abstract of this paper, we don't know whether adding a variable will decrease or increase the bias: http://www.sas.rochester.edu/psc/clarke/405/Omit.pdf
[1] Page 31 of https://pdfs.semanticscholar.org/49f8/49647aec895a598869113b...
[2] Annotated version of the key figure here: http://ethicussions.blogspot.com/2014/05/inequality-and-its-...
I am not suggesting the results are one way or the other, but let's all keep in mind that given any statistical phenomenon, we can control for the change.
i.e. if there is an increase in automation due to the minimum wage, which in turn displaces workers, a biased or naive researcher can "control for automation and technology trends"-- effectively eliminating the perceived effect of the price floor.
I'm not saying that this is what is happening here, as I haven't read the studies, but I wouldn't be surprised if this were the case given that they are claiming the law of demand doesn't apply.
The proper way to do min wgae testing is by comparing neighboring districts. If one county has a min wage hike its neighbors do not, then you can compare the outcomes of the affected county and use the other as a control.
When this is done, the effects of min wage hikes become clear: in the short run, employees are not immediately fired because businesses stay open. However, in the long run, fewer employment opportunities are available. This suggests that in some areas, a min wage hike can cause disemployment effects over the long term [0]
[0] http://voxeu.org/article/long-run-employment-effects-minimum...