There are two other less intuitive conclusions of the study: regional rates of major depression are completely uncorrelated (r=-0.10) with gun ownership; and - much more shockingly - regional rates of major depression are completely uncorrelated with regional suicide rates (r=0.00!). The latter conclusion, of course, casts doubt on the commonly-held belief that suicide is a symptom of a disease - depression - or the end-point of a disease process, rather than a rationally and freely chosen action. Interestingly, and again supportive of the suicide-as-decision hypothesis, regional rates of suicidal thoughts are correlated with suicide - though suicidal thoughts do not correlate with gun ownership.
You can read the study, "Association of rates of household handgun ownership, lifetime major depression, and serious suicidal thoughts with rates of suicide across US census regions," by D. Hemenway and M. Miller (Inj Prev 2002;8:313-316), if you have library or school access to Injury Prevention, but if you don't, I think it's important to give an idea of how careful and well-planned this study is. On why they chose to do a regional study with data averaged over ten years:
Because the stock of guns in the United States is so high (over 200 million guns in civilian hands) and because guns are highly durable goods, year-to-year variations in survey estimates of firearm ownership rates are as likely to reflect measurement error rather than actual fluctuations in firearm ownership levels. Handgun ownership data are, therefore, averaged over the 10 year study period to obtain more reliable estimates of regional handgun ownership rates.
On the limitations of studies comparing regional variables:
This study has various limitations. First, as in any ecological study, a concern is that the association found at the aggregate level does not exist at the individual level. For example, from our data, even if there is a regional level association between alcohol and suicide, we do not know if the individuals who are alcohol consumers are the ones more likely to commit suicide. However, from other studies we know that guns are the prime method of suicide in the United States, most people who use guns to commit suicide use family guns, and a gun in the home is a risk factor for firearm suicide.[footnote omitted] We thus have somewhat less reason to be concerned about the "ecological fallacy" with respect to the gun prevalence-suicide connection.
In short, the study is the wet dream of those who would like to restrict handguns in order to prevent suicide. Gun advocates disfavor this sort of logic when it means restrictions on handgun use for the general population, because they see a value to gun ownership; however, gun advocates such as the NRA are all too willing to sell out and cheer on this sort of logic when applied to people diagnosed with some sort of mental illness. No one seems to be considering the possibility that banning guns to reduce suicides is wrong because the right to commit suicide is valuable. Mark Daigle, writing (ironically) in Accident Analysis & Prevention (Volume 37, Issue 4, July 2005, Pages 625-632), typifies this assumption in the public health field:
The effectiveness of restricting access to certain means of committing suicide has been demonstrated, at least as regards toxic domestic gas, firearms, drugs and bridges. At the individual level, studies tend to indicate that many persons have a preference for a given means, which would limit the possibility of substitution or displacement towards another method. Similarly, the fact that suicidal crisis are very often short-lived (and, what is more, influenced by ambivalence or impulsiveness) suggests that an individual with restricted access to a given means would not put off his plans to later or turn to alternative methods. ["Suicide prevention through means restriction: Assessing the risk of substitution (A critical review and synthesis)"]
Restricting access to gun, toxic gas, drugs, and bridges reduces suicide, says Daigle - and that's good, right? If a "suicidal crisis" might be "short-lived," and if it might be characterized by "ambivalence or impulsiveness," isn't it good to prevent the suicide - for the suicide's own good?
I think we need to take seriously a very real alternate possibility - that thousands of people suffer so desperately that they often wish to kill themselves, and that if a suffering person chooses death, death is what is for his own good. Methods for "suicide prevention" that merely remove access to what Daigle calls preferred means is not good, but cruel - it actually increases the amount of suffering in the world, and does so by forcing suffering on a segment of the population. They do nothing to reduce the need for suicide - only to reduce the occurrence of suicide. This sort of "suicide prevention" is a form of masking the suffering of a population.
It is only good to prevent suicide in people who wish to commit suicide - who want to die - if life itself is good despite suffering, and if it is proper to force this value onto others who do not accept it. Only if suicide is inherently wrong - if dying is inherently worse than living - is it proper to use force, such as legal restrictions, to reduce the suicide rate. It is my firm commitment that life is not inherently good, and that dying is not inherently worse than living.
Banning tattoo needles, for instance, would probably reduce the rate of tattoos, just as banning guns might reduce the rate of suicide. But despite the impulsiveness and ambivalence that might characterize the decision to get a tattoo, the short-lived nature of the desire, and the permanence of the tattoo (n.b.: especially colored ink), most people support the right to get a tattoo. The fact that many people who were prevented from getting a tattoo are later glad to have been prevented from making the decision would not remove the repugnance of a tattoo ban. Advocates of suicide prevention through force and restriction must explain why dying, when freely chosen, is necessarily worse than getting a tattoo. A tattoo you may regret for your entire life - but suicide will result in no regrets, and no conscious suffering at all. This view is consistent with the idea that life may be assigned value by an individual living person - i.e., killing a person who wishes to live is still a wrong to that person, even if he feels nothing. But prohibiting suicide forces this view of life-as-necessarily-more-important-than-your-suffering on those who adamantly reject it.