Print Story Mathematics anxiety and two kinds of panic
Logic & Maths
By Alan Crowe (Fri Dec 24, 2010 at 08:23:44 AM EST) landsburg, sex ratio, expectation (all tags)
In a far away land the natives don't much like children, but must have a male heir. So each married couple keeps having children until they have a boy, then they stop. Does this skew the demographics?

Every couple has a boy, but half get a boy first time: one boy, no girl. Clearly the stopping rule skews the demographics in favour of boys. On the other hand I've falsely spun the stopping rule as pro-boy. The rule is actually "keep having lovely girls until a yucky boy comes along, then give up in disgust". Many families consist of many girls and one boy. Clearly the stopping rule skews the demographics in favour of girls. On the third hand the demographics are fixed by the 50:50 ratio of boys to girls. The stopping rule is irrelevant.

So there is the kind of panic when you cannot tell whether your answer is correct or not. Steve Landsburg is blogging the second kind of panic. Terror inside.


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