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Isn’t it amazing? If you flipped a coin ten thousand times the odds are unlikely that there would be within a small margin roughly the same number of heads as tails. Yet throughout history there have been relatively the same number of males as females born, within a small margin of difference, in every generation. You won’t find a 100 year period where the sex ratio at birth was 70% male, 30% female or 40% male, 60% female. Randomly, it should have been just as likely that the ratio would be 80%/20% as the likelihood it would be 50%/50%.
Baruch Hashem!
-Lior
Where’d you get your statistics about coins? I think with a sufficiently large sample, it would be very close to 50% each.
well then why is there a shidduch crisis 😉
Chulin 77b:
??? ??????? ?????? ???? ????? ????? ?????
Granted it’s talking about animal there.
Because Hashem wants it to be so…
Not true in China, where the one child policy led to a surplus of boys. There they have a true shidduch crisis. Hey, if all the Chinese boys converted, it would solve our shidduch crisis.
DaasYochid:
I think Lior’s point is that granted over thousands of years it shourd be pretty equal, just like over thousands of coin flips it would probably be relatively equal, but it shouldn’t necessarily be equal in any given period of time, say every year.
If there’s a large enough sample, it should be approximate equal in every generation.
You will find inequality in families – small sample. You will find equality in klal Yisrael and even in it’s sub-groups – large sample.
It is amazing that the opening poster is so ignorant of probability. And yehudayona is likewise ignorant. Both of you should go back to your statistics text books before you discuss statistics again.
Why do you think yehudayona is ignorant?
Is there anything in yy’s post to indicate otherwise?
Lior, your opening post shows a profound lack of understanding regarding statistics
“Isn’t it amazing? If you flipped a coin ten thousand times the odds are unlikely that there would be within a small margin roughly the same number of heads as tails.”
If it is an even coin the odds are extremly likely that the spread will be close (not exact) 50/50
As PAA points out over a short period you will get a wider distribution, and this is in fact the case (OF course short period is relative given an infinite number of coin flips 10,000 is a VERY short period)Though short period isnt the best term, few number of “flips” is better and this is the case. Consider a couple that has 2 children over the course of a year (or so) it obviously is not unusual if both are boys or girls, we see that often. But as the number of flips grows the closer to 50% you’d expect as in fact occurs. Even every year the number of “flips” isnt small in the U.S. alone it is around 4,000,000. And as expected it is near 50/50. But if you break down that statistic by State/County/City/Neighborhood/Block etc… You will find a wider spread in some areas (like the couple that had 2 children both boys) that “even out” over the long run.
A more interesting question:
If Hashem told you that you will be having five (or any other number) of children in your life and I am giving you two choices – they can either be all boys or all girls, which should I make it be?
What would you choose?
yehudayona: That is not due to biology, as a quick google search will tell you, but rather to female infanticide and abortion of females due to the one child policy.
nolongersingle: Both! Five boys and five girls.
OP: Actually the more coins you drop, the closer the average will be to 50%
I don’t see where yehudayona attributed it to biology.
um, was the OP always joseph? Idk why but I thought it was s/o else
Lior.
Lior is Joseph! Mods, you can’t say I didn’t call it. Twice. (Although mods didn’t let one of them through.)
Joseph
Your assumptions are incorrect. Statistically for a 50/50 event there is a huge difference in likelihood of it being 50/50 vs 80/20. The more times you “flip” the greater difference in likelihood. Given a large enough sample size the likelihood of even 52/48 can be infinitesimal kal v’chomer 80/20.
As a more visual example take 6 children. Since there are 2 possibilites per child (m/f), there are 2^6 = 64 possible combinations for all these children. (ie. MMMMMM, MMMMMF, FMMMMM, MMFFMF, etc..) So, because there is only 1 possible way for all to be male, the odds of 100% male is 1/64. Same with all female. The would make odds of 100% either way is only (1+1)/64 = 1/32.
However, to have 5 male and 1 female there are 6 different combination of that. MMMMMF, MMMMFM, MMMFMM, MMFMMM, MFMMMM, FMMMMM. That means there is a 6/64 chance that there will be 5 male and same for female. So, odds of there being 5 of either (which would be 83%) is 12/64 or 3/16 (approx 19%). This is more much more likely than 100% but not so likely.
4 males has 15 combinations MMMMFF, MMMFMF, MMFMMF, MFMMMF, FMMMMF, MMMFFM, MMFMFM, MFMMFM, FMMMFM, MMFFMM, MFMFMM, FMMFMM, MFFMMM, FMFMMM, FFMMMM. 4 females the same. That would be 30/64. So, 50/50 has 64-30-12-2 = 20/64 chance of happening.
To summarize likelihoods:
6M = 1/64
5M1F = 6/64
4M2F = 15/64
3M3F = 20/64
2M4F = 15/64
1M5F = 6/64
6F = 1/64
In other words, the closer you get to the 50% mark the more likelihood of it.
and so many pairs of posters just happened to be each other
Lior/joseph I’m not sure I would be proud to be the OP of this post. You claim “on a point that I was aware but slipped my mind – the horror” But the elementary statistics “slipped your mind” isnt a side point, it is the thrust of your OP
-ubiquitin
So I did some experimentation to demonstrate that as the sample size increases the percentage moves closer to 50%.
I used a computer to randomly generate a number, either 1 or 2 (representing male or female).
Results by sample size (ss):
ss 10 = 70%
ss 100 = 55%
ss 1000 = 48%
ss 10000 = 50.22%
ss 100000 = 49.808%
ss 1000000 = 49.9077%
ss 10000000 = crashed the computer
In terms of distance from 50%:
ss 10 = 20
ss 100 = 5
ss 1000 = 2
ss 10000 = .22
ss 100000 = .192
ss 1000000 = .0923
ss 10000000 = crashed the computer
It is clearly getting significantly closer to 50% as the sample size gets larger. In fact even a sample size as small as 100 was pretty close to 50%.
Was it worth blowing two computers on that?
DY: He only blew one. It’s the same math.
Oh, then I guess it’s no big deal.
“Many Chinese parents manipulate the results by aborting female pregnancies”
This happens in much of India, too.
In there United States there are about 105 baby boys born for every 100 baby girls. The likelihood that that difference is due to chance is extremely low.
It’s Hashem’s way of allowing for a slight age gap.
Was it worth blowing two computers on that?
DY: He only blew one. It’s the same math.
Oh, then I guess it’s no big deal.
The computer was back to normal after about 20 minutes. Although, Sam’s point notwithstanding, I did actually crash it twice – after it crashed from the 10000000, I tried doing 10 separate 1000000 (concurrently) and that also crashed the computer.
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