2014년 3월 15일 토요일

Differential pressure


  • p(pearl) = 40%
  • p(blue|pearl) = 30%
  • p(blue|~pearl) = 10%
  • p(pearl|blue) = ?


Differential pressure between the two conditional probabilities,  p(blue|pearl) and p(blue|~pearl) 의 개념



it's easier to see why the final answer depends on all three probabilities; it's the differential pressure between the two conditional probabilities,  p(blue|pearl) and p(blue|~pearl), that slides the prior probability p(pearl) to the posterior probability p(pearl|blue).

...
you can see that when the conditional probabilities are equal, there's no differential pressure - the arrows are the same size - so the prior probability doesn't slide between the top bar and the bottom bar.



In the frequency visualization, ... The bottom bar is shorter than the top bar, just as the number of eggs painted blue is less than the total number of eggs.


The gif file created from the applet at http://yudkowsky.net/rational/bayes

2014년 3월 10일 월요일

Stupid Smart Stuff - "a dangerous myth"


Interesting article by Prof. Don Norman

Stupid Smart Stuff: Watches and Automation :
How silly. The notion that we can have automated or semi-automated cars as long as the driver is watching over them is a dangerous myth. 

It is a myth that people can maintain control when they have nothing to do for a long period.

This myth is well understood in the military and in commercial aviation. 

http://networkedblogs.com/UA6IZ