It's not that it's not valuable, it's that one must be careful in using it.Exactly, that is why it is not very valuable.
As I pointed out, it's perfectly valid to draw general conclusions from the results or look for counterexamples and trends, but it's a mistake to try to calculate numbers.
He probably has access to raw data that would answer the question, it's just a matter of compiling it and doing the calculations.As I have mentioned before, I have a friend that is an actuary and he is very well paid to do just that.
I seriously doubt that any insurance company will pay him to do so, however, since it's not in their interest (limiting their liability) to provide statistics showing that armed self-defense is an advantage in any situation.