Or intelligent people may be more likely to apply cognitive techniques (perhaps they experience depression earlier and/or more commonly which may build resilience) and/or may be more likely to seek professional advice (e.g. because they see the value, move in circles in which it is more acceptable, or make more money and can afford to).

"Suicide" is simply too rare, and too broad a category. Is not using a seat belt suicide? Is a heroin overdose? Is standing on a cliff to estimate what it would be like to jump and loosing ballance at the thought of it?

How many suicides were there in the 60000 studied, perhaps 10? That's not enough to derive a meaningful result, I think.

Edit: My estimate would be roughly correct, sad enough, ignoring my doubts on suicide as a cultural rather than medical category: http://news.bbc.co.uk/2/hi/uk_news/scotland/5297916.stm

I'm not sure how you got to 'obviously'. Could you elaborate?

How is that obvious?