Reply #50: It has exactly the same problems as Kellermann's 1993 study

[Euromutt]

The fundamental element of the protocol is the same shitty one as Kellermann's, namely comparing a study population of shooting victims to a control group of people who haven't been shot. That's your first confounding factor right there: your study subjects are by definition more likely to have been shot (chance of 1, in fact), because that was what you selected them for. Similarly, your control group are less likely to have been shot (chance of 0), because that was what you selected them for.

So you've got one bunch of people with bullet holes, another bunch without, and essentially you're asking "why do these guys have holes while those guys don't?" There's a whole raft of reasons why, but you're trying to isolate how much effect one of those factors has. For this, researchers use a technique called "multiple regression" in an effort to compensate for all the other variables, but the fact is that you can never be 100% certain that you actually have identified every variable.

That's why the validity of econometric modeling (which is what this study is) can only be tested in one way: its ability to make predictions better than chance. That's why a single econometric study is worthless; unless the model can be used to make predictions that stand up to testing, it is evidence of exactly nothing. In the words of Ted Goertzel (http://crab.rutgers.edu/~goertzel/mythsofmurder.htm):

When presented with an econometric model, consumers should insist on evidence that it can predict trends in data other than the data used to create it. Models that fail this test are junk science, no matter how complex the analysis.

Junk science is what Kellermann's work is, and it's dollars to donuts that it's what this study is too. Especially because the press release makes claims eerily similar to Kellermann's, and in Kellermann's case, even a cursory reading of the actual study showed that its findings really didn't support the authors' conclusions, and the press release seemed to have been written about a completely different study.