kcab asked whether the Secret Service report on targeted school violence looked at attacks that were prevented as well as attacks that were carried out.
The answer is 'no.' The report looks only at attacks that were actually carried out.
The bad news, I suspect, is that the reason the report didn't look at attacks that were prevented is simply that attacks never are prevented. Not by school authorities, at any rate.
I doubt many planned school shootings have been prevented by parents, either. Parents never know about the plans -- none of the adults in the student's life knows. There are often kids who know, but no adults. And kids don't tell.
Once a student plans a shooting attack on his school, it's up to him whether he goes through with it or not.
At least, that's the way I read the findings.
update: I read the findings wrong.