In medicine it is even worse as there are so many vested interests, who do you listen too?

Sometimes the books’ maths gets a bit hairy but generally I’ve learned an awful lot from it. I’m now hooked on the power of conditional probability and I’d like to give an example of how its lessons can be used in everyday life.

I’m currently looking for a job so I speak to recruiters every day. A few weeks ago I was talking to a recruiter about a position working with computers. I’ll leave the details out, but one of the required skills was working with an old UNIX system. Another requirement was working with an unusual customer relationship management system and the last requirement was fluency in a SE Asian language.

If I remember correctly, my conversation with the recruiter went something like this:

“What chances do you think you have of finding someone with all three?“
“The problem is the language fluency. Of the fifty applications we’ve received so far, only 5 can speak that language at all.“
“How about the other skills?“
“10 of the applicants have the UNIX experience, and maybe 5 in total have the CRM experience“
“Right … so .. how do you rate your chances of finding someone with all three then?“
…
“We’ll probably only respond to the five or so that will have all three”

(She’s concluded that 10% of the fifty applicants will meet all of the requirements. However, the correct figure is 0.002%, meaning she will have to get through roughly another 450 applications to find someone with all three of the skills)

Notwithstanding the fact that she has a job and I don’t right now, this example does show that statistics and conditional probability are hugely undervalued especially by the people who need to understand them most.

I found Stuart Sutherland’s book ‘Irrationality’ to be an excellent intro into how people miscalculate risk too.