[tinymollusk]

Doesn't his "99/100" give us a much better idea of his confidence in his own knowledge, compared to something more vague like "usually" or "the vast majority of the time"?

I ask because I've been studying how to make better decisions, and one of the techniques is to use numbers instead of the easily misinterpreted words. The famous example is the Bay of Pigs decision -- Kennedy was told the invasion plans had a "fair" chance at succeeding. The advisor was later interviewed and said that he meant 3-1 against as "fair odds", which could easily have changed Kennedy's decision.

[kbenson]

> Doesn't his "99/100" give us a much better idea of his confidence in his own knowledge, compared to something more vague like "usually" or "the vast majority of the time"?

Sure, it gives an idea of confidence, but we haven't established that confidence as worth anything yet, and we're being fed numbers to add an air of legitimacy to a statement which doesn't really have any otherwise. Unless someone has actually examined 100 cases, it's just bluster. It's like saying "oh, that never happens" to discount an argument entirely. It's not helpful to a real discussion.

> The advisor was later interviewed and said that he meant 3-1 against as "fair odds", which could easily have changed Kennedy's decision.

The adviser was likely also someone with previously established expertise in this area, which means that opinion might be worth something without supporting evidence. Additionally, giving actual predicted odds is different than falling back on on a colloquialism that almost never literally means 99 times out of 100 or 99%, but instead is meant to convey "almost always", and using terminology like that in a conversation without any supporting evidence isn't useful.

[tinymollusk]

I agree about this particular comment -- your interpretation is likely correct. I was just trying to connect it larger, to the decision making skills that I'm working on (and thought might be interesting to a HN audience).

FWIW, the Pigs incident is widely cited as an example within this sphere. It has nothing to do with whether the advisor was previously skilled -- it has more to do with thinking about how people understand and use the information I communicate. (and that using numbers instead of words seems to be considered "best practice" in the decision making community).