No I have not. I quote from page 173: "there is a positive
relationship [of firearms ownership] with firearms murder but not with
criminal homicide generally." See table 9.2 on page 174.
I should note again that Bordua felt that this relation was spurious
but that his reasoning was faulty. In any case, the relationship does
exist
Rick Cook writes:
So Bourda found what he considered a spurious relationship and you trust
his work enough to believe that the relationship existed, but you don't
believe the relationship was spurious.
All right then: The relationship exists (provided Bordua did not make a
mistake in his calculations). As I'm sure you are aware, finding
correlations is fairly mechanical, while giving causal interpretations
of those relationships is decidedly more tricky.
How does that work in this case? Do you know why Bourda considered the
relationship spurious? Why do you consider it not to be spurious?
Why Bordua decided the relationship was spurious:
He looked at male and female ownership separately and found that each
one had a significant positive correlation with gun murder. Then he
built a multivariate model using both male and female ownership. Only
the coefficient associated with female ownership was significant in
this model. Since only 11.5% of gun murderers were female, it is
unreasonable to expect female ownership to cause gun murders, so
Bordua concludes that gun murders cause female gun ownership, and that
the relationship between male ownership and gun murders was spurious,
engendered by the correlation between male and female ownership.
What's wrong with his reasoning:
Essentially he is offering the following causal explanation for the
correlation between male gun ownership and gun murder: gun murders
cause female gun ownership which causes male gun ownership. Certainly
it is plausible that gun ownership by some subgroup of the population
of a county causes gun ownership by some other subgroup, since each
gun owner will have some chance of introducing another person to
firearms ownership. However, Bordua has the direction of causality
wrong. More than 90% of the gun owners were male. This means that
while female ownership causes male ownership to a small extent, it is
mostly male ownership that causes female ownership. Consequently,
Bordua's causal explanation is less plausible than this one: "Male
ownership causes gun homicides and female ownership."
Please note that I am not claiming that this one is necessarily
correct, but that we cannot dismiss the correlation between gun
ownership and gun murder as spurious.