Positive predictive values and gun control

The US has a number of workplace and school shootings, and each incident goes the same way. Media dig up events from the perpetrator's past (putting the perpetrator's name everywhere when the perpetrator's name really should forgotten, and the victims the ones who are remembered), including criminal record, complaints from co-workers, qualitative assessments of the shooter's mental health, and random anecdotes, and all of these events are assembled to answer the question of whether someone could have known that the perpetrator was so crazy.

While some of these incidents from a perpetrator's past are indeed crazy, they have poor positive predictive value: the most recent shooter apparently punched a woman over a booster seat at an IHOP. But such ironic and strange incidents happen all the time, which I know as an avid reader of News of the Weird. Attempting to predict who will go bezerk is like looking for a needle in a haystack: many people do minor strange, crazy things, and even do so multiple times, but most people who do minor strange things will not commit homicide. Even looking at more severe incidents, such as shooting a brother at age 20, may not necessarily predict future violence. Though allegedly sending a bomb to a dissertation committee member seems more likely to predict future violence, she was cleared of that charge.

Attempting to predict who will snap begs the question. We can't. Even if we had Big Brother comprehensive databases of every person's past, and were willing to disregard rules of evidence and dropped charges, we couldn't predict severe violence. The real issue is not which people are likely to snap, but rather why our gun control policy allows people such easy access to firearms that when they do snap they can do so much damage. Human psychology is fallible, but in countries without easy access to firearms, the damage comes in the form of broken objects, bruises and broken bones, and perhaps even a stabbing. Firearms create more damage, and damage that is most likely to be deadly.

. . .

Speaking of News of the Weird, here's one from last year about a Yale PhD and professor:

Love Can Mess You Up: Before Arthur David Horn met his future bride Lynette (a "metaphysical healer") in 1988, he was a tenured professor at Colorado State, with a Ph.D. in anthropology from Yale, teaching a mainstream course in human evolution. With Lynette's guidance (after a revelatory week with her in California's Trinity Mountains, searching for Bigfoot), Horn evolved, himself, resigning from Colorado State and seeking to remedy his inadequate Ivy League education. At a conference in Denver in September, Horn said he now realizes that humans come from an alien race of shape-shifting reptilians that continue to control civilization through the secretive leaders known as the Illuminati. Other panelists in Denver included enthusiasts describing their own experiences with various alien races. [Rocky Mountain Collegian, 9-28-09]

NY Times on the undergraduate sexual economy

Just as Katherine Bogle found: The NY Times reports that women are outnumbering men on campus, and turning to hookups in hopes of hooking a man. Based on both what I've learned anecdotally and also read in Rachel Greenwald's qualitative study of dating among adults, that's counterproductive. As someone told me when explaining why he thought early sex was intrinsically casual sex, "Everyone knows that if you have sex on the first date, you'll never see each other again."

If their concerns are long term, as many of these women and those in Bogle's study said, the women's decision to eliminate half the men to start with is also counterproductive. The article describes a campus that is 60% female where half the men are undesirable, and half of the desirable are coupled. Take a campus of 1000 students (all straight): 500 available women, 200 "undesirable" men, 100 available "desirable" men, and 100 each coupled "desirable" men and women. Effectively, the women have created a situation where the gender ratio is 5:1 female to desirable male, when it would otherwise be 5:3. Of course all the women expect that they are going to be the lucky 10% in a couple, so it would seem that this situation doesn't hurt them. In fact, since it seems likely that even couples are more unstable in a 5:1 gender ratio than a 5:3 gender ratio, labeling half the men as undesirable hurts even coupled women.

As one woman quoted in the article said, "As for a man’s cheating, “that’s a thing that girls let slide, because you have to. If you don’t let it slide, you don’t have a boyfriend.”" (Obviously counterproductive, no matter what the gender ratio is.)