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Wasn’t their some policy saying that rural mothers could have a second child if their first was a girl? If they each had the maximum number of children, it woul

Wasn’t their some policy saying that rural mothers could have a second child if their first was a girl? If they each had the maximum number of children, it would lead to an average of about 1 boy and 0.75 girls per rural mother.

lozenge 5y ago
Yes, the article saying the one child policy remained untill2016 is an oversimplification. There were already exceptions introduced including when both parents had never had any siblings.
areyousure 5y ago
50% B + 25% GB + 25% GG = 0.75 B + 0.75 G. Can you think of a law ("stopping rule") that could even get the expected number of boys higher than the expected number of girls?
- dmichulke 5y ago
  For gambling it would would work if you do a "double or nothing" type of bet. Unfortunately, you'll be quickly rate limited by birth capacity, even if you somehow manage to double the amount of children per birth. Also, asymptotically, you'll still be around a 50% split.
  - waterhouse 5y ago
    Assuming no selective-abortion shenanigans, every child you have is expected 50% male, 50% female (barring e.g. unusual men who only produce sperm of one gender—I think that exists but is extremely rare), so there's no possible strategy that leads to an uneven gender split, probability-wise. But I think there were selective-abortion shenanigans, and that the policy was effectively in response to them. If we assume each family wants, as its first objective, to maximize the number of sons, and, as its second objective, to maximize the number of daughters, then each selective-aborting family would have exactly one daughter followed by one son under such a policy.
    - alisonkisk 5y ago
      Parent was talking about having indentical multiples: 1 girl, 2 girls, 4 boys, stop.
- dandellion 5y ago
  Is that correct? The left side adds to 1 and the right to 1.5.
  - areyousure 5y ago
    50% * 1 + 25% * 2 + 25% * 2 = 1.5.
    - dandellion 5y ago
      Ahh, got it.
  - function_seven 5y ago
    Rewrite it as .50(B) + .25(G+B) + .25(G+G) = .75(B) + .75(G) and it balances.
- dan-robertson 5y ago
  You’re totally right. I guess what I wrote above doesn’t hold water. And an intuitive way to think about it is that each child does not know the sex of the child before it—if you had a line of children and each mother simply took the next child in the line, you would expect a 50-50 sex distribution even if mothers followed the rules given above.
- mlyle 5y ago
  It's actually even worse for the assertion than this, because the genders of babies from the same parents are not independent statistical events. So, if you have 1 B, you stop. If you have 1G, you may have another child, which is somewhat more likely to be a girl than a boy. So you'd expect this policy (in isolation) to produce a surplus of girls.
seanmcdirmid 5y ago
Those were local family planning board decisions and never really applied in the cities. In fact, family planning was applied so unevenly across China that some people got in trouble for having one kid at all (because of corruption), or on their second kid had to give up their government jobs even though they technically had rural hukou.
jan_Inkepa 5y ago
If everyone in the planet gets to toss a coin, and if it comes up heads you get to toss it again, that doesn't mean that there are any more tails than heads, each coin toss is just a coin toss, independent from any other.
- deleted 5y ago
  [deleted]
csa 5y ago
> Wasn’t their some policy saying that rural mothers could have a second child if their first was a girl? Yes. https://en.m.wikipedia.org/wiki/One-Child_Policy https://en.m.wikipedia.org/wiki/One-Child_Policy “Peasants” (their term, not mine) and minorities* could have more than one. It was very, very common. Apparently half of the country was effectively under a two-child policy. * There are 55 recognized minority groups in China (https://en.m.wikipedia.org/wiki/Ethnic_minorities_in_China https://en.m.wikipedia.org/wiki/Ethnic_minorities_in_China).

lozenge 5y ago

Yes, the article saying the one child policy remained untill2016 is an oversimplification. There were already exceptions introduced including when both parents had never had any siblings.

areyousure 5y ago

50% B + 25% GB + 25% GG = 0.75 B + 0.75 G. Can you think of a law ("stopping rule") that could even get the expected number of boys higher than the expected number of girls?

dmichulke 5y ago
For gambling it would would work if you do a "double or nothing" type of bet. Unfortunately, you'll be quickly rate limited by birth capacity, even if you somehow manage to double the amount of children per birth. Also, asymptotically, you'll still be around a 50% split.
- waterhouse 5y ago
  Assuming no selective-abortion shenanigans, every child you have is expected 50% male, 50% female (barring e.g. unusual men who only produce sperm of one gender—I think that exists but is extremely rare), so there's no possible strategy that leads to an uneven gender split, probability-wise. But I think there were selective-abortion shenanigans, and that the policy was effectively in response to them. If we assume each family wants, as its first objective, to maximize the number of sons, and, as its second objective, to maximize the number of daughters, then each selective-aborting family would have exactly one daughter followed by one son under such a policy.
  - alisonkisk 5y ago
    Parent was talking about having indentical multiples: 1 girl, 2 girls, 4 boys, stop.
dandellion 5y ago
Is that correct? The left side adds to 1 and the right to 1.5.
- areyousure 5y ago
  50% * 1 + 25% * 2 + 25% * 2 = 1.5.
  - dandellion 5y ago
    Ahh, got it.
- function_seven 5y ago
  Rewrite it as .50(B) + .25(G+B) + .25(G+G) = .75(B) + .75(G) and it balances.
dan-robertson 5y ago
You’re totally right. I guess what I wrote above doesn’t hold water. And an intuitive way to think about it is that each child does not know the sex of the child before it—if you had a line of children and each mother simply took the next child in the line, you would expect a 50-50 sex distribution even if mothers followed the rules given above.
mlyle 5y ago
It's actually even worse for the assertion than this, because the genders of babies from the same parents are not independent statistical events. So, if you have 1 B, you stop. If you have 1G, you may have another child, which is somewhat more likely to be a girl than a boy. So you'd expect this policy (in isolation) to produce a surplus of girls.

seanmcdirmid 5y ago

Those were local family planning board decisions and never really applied in the cities. In fact, family planning was applied so unevenly across China that some people got in trouble for having one kid at all (because of corruption), or on their second kid had to give up their government jobs even though they technically had rural hukou.

jan_Inkepa 5y ago

If everyone in the planet gets to toss a coin, and if it comes up heads you get to toss it again, that doesn't mean that there are any more tails than heads, each coin toss is just a coin toss, independent from any other.

deleted 5y ago
[deleted]

csa 5y ago

> Wasn’t their some policy saying that rural mothers could have a second child if their first was a girl? Yes. https://en.m.wikipedia.org/wiki/One-Child_Policy https://en.m.wikipedia.org/wiki/One-Child_Policy “Peasants” (their term, not mine) and minorities* could have more than one. It was very, very common. Apparently half of the country was effectively under a two-child policy. * There are 55 recognized minority groups in China (https://en.m.wikipedia.org/wiki/Ethnic_minorities_in_China https://en.m.wikipedia.org/wiki/Ethnic_minorities_in_China).