Tim Lambert (deltoidblog AT gmail.com) is a computer scientist at the University of New South Wales.
The study controlled for literally dozens of other factors, including criminality and illicit drugs. Furthermore the extra homicide risk associated with firearm ownership was not from shootouts between drug dealers or gangs, but domestic homicides.
Dr. Paul Blackman writes:
No. The study measured about 2.5 dozen items, but controlled for about six -- with a number of items prevented from measurement by matching the controls (race, age group, sex, etc.)
All right. They controlled for four factors by matching and another six in the multivariate analysis. The other 2 dozen measured items could have been controlled for if they had proved to be statistically significant.
None of the items measured or controlled for involved drug trafficking, as opposed to simple drug use.
Though you would expect this to be strongly correlated with arrested and with drug use.
One would certainly have expected a higher-than-average rate of domestic homicide when the three-fourths-plus of homicides outside the home were excluded -- although non-gun and domestic homicides were also minimized a bit by excluding the slayings of pre-adolescents in the home.
Yes, the fraction of homicides that were domestic would be higher than for homicides in general, but that wasn't my point. The "extra" homicides associated with gun ownership weren't from drug dealers shooting each other but domestic ones. That is, the alternative explanation: "Drug dealers own lots of guns and are likely to killed by other criminals" does not fit the data.
