On conservative commentary website Stream.org, statistician William M. Briggs (who, take it for what it's worth, opposes same-sex marriage) offers a critique of the study's methodology and conclusion, as well as the conclusion that the study expressly does not make, but that the headlines have made:
https://stream.org/no-a-study-did-not-show-that-same-sex-mar...
A few interesting snippets from his critique:
> A weighted 8.6% to a weighted 8%, they say. This is a 7% reduction, all right, but a minor tweak in the actual weighted number. The numbers are weighted averages across several states and the result of a statistical model called a linear regression. The 0.6 drop is not observed, but is the output from a model.
> The numbers within states is anything but straightforward (the authors provide graphs). For instance, some states show reported suicide attempts increasing after gmarriage (New York, Maine, New Hampshire and Vermont, for example). The graphs also indicate a general decline in rates before gmarriage and continuing afterwards (see their Fig. 3).
> putting Ebola in the model works equally well with gmarriage to explain the data. So do the disasters of those crashing Malaysian airliners, or the fighting in Ukraine and Crimea. So does the 2014 Winter Olympics!
One other point that Briggs makes only indirectly, but bears mentioning, is that measuring the number of self-reported unsuccessful suicide attempts only provides us with part of the picture; we can't make any firm conclusions about what its rise or fall says about suicide prevention unless we also know the number of _successful_ suicide attempts. For instance, it might be the case that some suicide prevention factor reduces the likelihood that any given suicide attempt is successful. Maybe hospitals have gotten better at reducing the mortality rate of intentional overdoses. In such a case, the rate of suicide attempts might remain relatively flat, but the rate of unsuccessful suicide attempts would rise, and the rate of successful suicide attempts would fall.