In Japan, where the suicide rate is quite high but guns are banned, they use rope. So it is accurate to state that rope ownership is closely tied to suicide rates in that country.

Using that same methodology, it is easy to do the same with guns and suicide. States with higher estimated levels of gun ownership had higher incidents of gun-related suicides, according to a new paper in the American Journal of Public Health which covers 33 years, from 1981 to 2013, and the authors claims is the most comprehensive analysis of the association between gun ownership and gender-specific suicides rates among the 50 U.S. states. 

The analysis found that firearm ownership was a significant predictor of male firearm suicide rates, which increased 3.3 per 100,000 for each 10 percent increase in gun ownership. For women, firearm suicide rates increased 0.5 per 100,000 for each 10 percent increase in gun ownership. The study also found an association between gun ownership rates and suicides by any means (including non-gun-related acts) among males, but not among females.

Over the 33-year study period, the mean estimated percentage of gun ownership ranged from a low of 12.2 percent in Hawaii to a high of 72.8 percent in Wyoming, with an average for all states of 41 percent. Hawaii had the third-lowest suicide gun suicide rate for males (4.8 per 100,000) among all states, while Wyoming had the highest rate (26.1 per 100,000). Massachusetts, with the lowest gun suicide rate in the country for men (4.2 per 100,000) had the second-lowest gun ownership rate.

The mean adjusted gun suicide rate among women over the study period ranged from a low of 0.40 per 100,000 in New York to a high of 4.2 per 100,000 in Nevada. The average gun suicide rate for both genders declined slightly from 1981 to 2013.

This is in contrast to other studies exploring the association between firearm ownership and suicides, which did not find any relationship. The authors believe that by analyzing three decades worth of data, examining gender-specific suicide rates, and accounting for a host of state-specific factors that could potentially confound the association, they had controlled for as many variables as possible. They believe they have controlled for income, education divorce rate and crime, among many other factors.

There is just one problem - with no state-level data on firearm ownership, they had to use a "proxy measure" of firearm ownership that estimates ownership based on the percentage of suicides in which a firearm was used and a state's hunting license rate. They believe their "well-established" proxy has a 95 percent correlation with survey-measured gun ownership rates, but that same methodology, these authors also said they had established that:

(1) Zebras evolved stripes due to flies
(2) Famous paintings are proof of climate change
(3) Bicep size correlates to political conservatism.
(4) A lack of vitamins is linked to more autism

They somehow believe banning guns would reduce suicide - in other words, that gun ownership causes mental illness. And find data to affirm it, which shows that the scientific method has left the building. For example, they claim that if the firearm ownership in Wyoming dropped from 72.8 percent to 41 percent (the average for all states), the male firearm suicide rate could be expected to decline by 38 percent, and the female rate by 56 percent. Overall male suicide rates in Wyoming, including those by means other than guns, would be expected to fall 16 percent, based on the study's model.