A recent study has found that, surprisingly, the risk of serious injuries to workers is higher in industries that are monitored by government safety inspectors than in industries that are not so monitored.
Given that
Government safety inspectors monitor some industries and not others.
Why is it that
The risk of serious injury to workers is higher in the monitored industries than in the unmonitored ones?
Evaluate
Safety inspection is supposed to make workplaces safer, so the natural expectation is that monitored industries would have lower injury rates. The study finds the reverse. Two kinds of explanation could fit. Either monitoring somehow makes things worse, which is hard to believe, or the comparison is lopsided because the monitored industries were already more dangerous before any inspector arrived.
The second route is the Causal Difference-Maker to look for. If inspectors are sent precisely to the industries where injuries are most likely, then the monitored group is dangerous by selection, and monitoring could be reducing injuries there while the rate still exceeds that of the inherently safe industries nobody bothers to inspect. An answer that explains why the monitored industries would be riskier with or without inspectors resolves the finding. An answer that only says inspectors are ineffective explains why monitored industries are not safer, not why they are more dangerous.
Goal
Find the answer showing that the industries chosen for monitoring are the ones with higher injury risk to begin with.