A total of 622 suicides were reported among students attending 645 distinct campuses from 2004–2005 through 2008–2009. Adjusting for gender in the population at risk of 14.9 million student-years and for the source of these data, the student suicide rate of 7.0 was significantly and substantially lower than for a matched national sample. Suicide rates by firearm were significantly and substantially lower for both female and male students. Hanging was significantly and substantially lower for male students, less prominently so for female students. It is principally the ninefold decrease in the availability of firearms on campuses (vs. homes) and secondarily other features of the campus environment that are the bases for lower student suicide rates.If the author had found that hanging as a suicide method was not significantly lower among college students, he might be able to make the case that college restrictions on gun ownership explain the lower gun suicide rate. I am hard pressed to see how gun restrictions on college campuses explains the lower rate of hanging suicides, nor am I aware of any colleges that limit possession of rope, sheets, or shirts.
UPDATE: The more I think about it, it might be that the decline in gun suicides was more than the decline in hanging suicides; that could be evidence that students were less likely to commit suicide in the fairly supportive college environment. A disparity in the decline between gun and hanging suicide rates could indicate that gun availability increases the risk of suicide. But a disparity might also indicate some fundamental difference between college students and their stay-at-home counterparts, perhaps related to depression or schizophrenia (most of which are big players in suicides in this age range).