Timeline for Google question: In a country in which people only want boys
Current License: CC BY-SA 2.5
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 4, 2017 at 6:43 | comment | added | Ovi | I don't get your comment about the stock market; if you always sell higher than you buy, how can you stay at zero? | |
| Mar 12, 2010 at 16:15 | comment | added | vonjd | Ah, ok... so I should change my answer by taking out the martingale and stopping time part, adding the Strong Law of large numbers and keeping the rest, right? | |
| Mar 12, 2010 at 16:02 | comment | added | Douglas Zare | The Strong Law of Large Numbers means the proportion returns (in fact, converges) to the mean almost surely. Martingales have no restoring force. Given that there have been 3 flips, and there have been 3 heads and no tails (proportion 3/(3+0) = 1), then the expected proportion after the 4th flip is 7/8, not 1. | |
| Mar 12, 2010 at 15:01 | comment | added | vonjd | Hmmm, could you give some reference for an explanation or a proof? Thank you! | |
| Mar 12, 2010 at 14:01 | comment | added | Douglas Zare | The difference between the count of girls and boys is a martingale, but the proportion of girls in the population is NOT a martingale. You can't apply the optional stopping theorem for martingales because the proportion is not a martingale. | |
| Mar 12, 2010 at 11:36 | history | edited | vonjd | CC BY-SA 2.5 |
added 308 characters in body; added 140 characters in body
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| Mar 12, 2010 at 11:34 | comment | added | Tom Leinster | It seems wholly intuitive to me too. However a couple decides whether to make another baby --- prayer, quality of the moonlight, desire to have a boy --- the proportion of babies born will always be 50-50. | |
| Mar 12, 2010 at 11:09 | history | answered | vonjd | CC BY-SA 2.5 |