All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars
 perplexus dot info

 Is it true? (Posted on 2016-05-02)
If the proportion of blonds among blue-eyed people is greater than among the population as a whole, is it also true that the proportion of blue-eyed people among blonds is greater than among the population as a whole?

Comments: ( Back to comment list | You must be logged in to post comments.)
 Simpson's Paradox (spoiler) | Comment 1 of 2
Yes.

Let a = # of blonde blue eyes
b = # of blonde non-blue eyes
c = # of non-blonde blue eyes
d = # of non-blonde non-blue eyes

Then a/(a+c) > (a+b)/(a+b+c+d)

Multiply by (a+c)/(a+b) to get
a/(a+b) > (a+c)/(a+b+c+d), and the YES is proven.

/************************************/

I have been a little formal here, because intuition fails sometimes. See link to Simpson's Paradox, which I always find counter-intuitive.

Edited on May 2, 2016, 9:19 am
 Posted by Steve Herman on 2016-05-02 09:19:15

 Search: Search body:
Forums (1)