In other words, the NCS only counts defensive uses against crimes.
Andy Freeman said:
Wrong. NCS doesn't get into defensive uses unless the victim thinks
that a crime occurred even if it was successfully self-defended
against. As in "Have you been the victim of a crime?" Someone who
successfully self-defended against an armed robber might well answer
"no". They weren't a victim. Yet, that's a self-defense against
crime, one that the NCS wouldn't ever find out about.
In fact the NCS does not ask "Have you been the victim of a crime?".
Andy appears to have made that question up. The relevant questions to
Andy's example are "Did anyone TRY to rob you?" and "Did anyone
threaten you with a weapon?"
Let's suppose for the moment that Andy's claim is true, and that this
explains the enormous discrepancy between the NCS estimate of defences
(80,000), and the 1,000,000 figure that some people here seem to
believe. What are the implications?
(1) The people who designed the NCS surveys are incompetent. NCS is
supposed to measure attempted crimes, but only finds out 10% of them.
Wrong. That isn't an implication. NCS is interested in victims.
These people don't necessarily consider themselves victims, and NCS
isn't interested in finding the ones that don't.
Can you provide some evidence for this remarkable claim? Like an NCS
document where they state "we're only interested in people who
consider themselves victims". Or perhaps a screening question where
they ask "do you consider yourself a crime victim?" OR did you make
this one up too?
(2) NCS data on completion rates of crimes is utterly worthless since
it is based on only 10% of attempted-but-not-completed crimes.
Wrong again. Some people may be victims even though the crime wasn't
completed.
So? How does this address the point I raised?
People who successfully self-defend are not necessarily
like everyone else who was a target of an unsuccessful attack.
Yes, so if completion rates are lower for "self-defence with a gun"
you cannot infer that guns are more useful for self-defence.
(BTW - Consider the crime "attempted murder".)
Certainly. A victim survey on murder would discover that the
completion rate for murder was 0%, irrespective of self-defence
measures used. Because the survey is biased (towards people who are
still alive) it tells us nothing useful about the success rate of
would-be murderers. Similarly, if the NCS is, as you claim, biased
away from successful defenders, it tells us nothing useful about crime
completion rates.
NCS data can be quite useful for many purposes without being able to
tell us about everything.
Certainly, but you want to reject the bits that do not support your
political beliefs and accept the bits that do.