Re: @ Graham Cobb
I have argued in another reply why the stats are, unfortunately, completely broken because of the impact of selection bias on the process.
However, even if they were right, profiling is never the right option.
* Individuals != profiles. In our society, each person should be treated equally, and are equally innocent until proven guilty. Even if 99% of people fitting a profile were criminals, that would not make it right to discriminate based on that profile.
* Change can only happen if people can break away from stereotypes and profiles. Even if profiling catches more criminals but it does nothing to encourage people to adopt another course.
* There are plenty of criminals who do not fit the profile. Why should they get away scot-free?
Instead of profiling, the answer is more police on the beat, visible, engaged and, most importantly, accessible to and supported by the community. If the community sees the police as effective, and fair, police will be able to actually have an impact on crime.
Policing is hard. Very hard. Deliberately so: society needs a police force who are fair and effective but respectful and with limited powers. Giving the police crap tools (and resources and training) just makes their work even harder and society sees negative benefit.