# Why are there approximately as many boys as girls?

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Viewing 35 posts - 1 through 35 (of 35 total)
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• #614987
Joseph
Participant

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

#1063796

Where’d you get your statistics about coins? I think with a sufficiently large sample, it would be very close to 50% each.

#1063797
cozimjewish
Member

well then why is there a shidduch crisis π

#1063798
Patur Aval Assur
Participant

Chulin 77b:

??? ??????? ?????? ???? ????? ????? ?????

Granted it’s talking about animal there.

#1063799
someoneMe2
Member

Because Hashem wants it to be so…

#1063800
yehudayona
Participant

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.

#1063801
Patur Aval Assur
Participant

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.

#1063802

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.

#1063803
nfgo3
Member

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.

#1063804

Why do you think yehudayona is ignorant?

#1063805
Joseph
Participant

Many Chinese parents manipulate the results by aborting female pregnancies due to the preference for a male child and China’s one-child limit.

#1063806

Is there anything in yy’s post to indicate otherwise?

#1063807
Joseph
Participant

The opening point that was stressed (that he replied “not true” to) is that there is a natural balance between the genders.

#1063808
ubiquitin
Participant

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.

#1063809

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?

#1063810
Torah613Torah
Participant

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.

#1063811
Torah613Torah
Participant

OP: Actually the more coins you drop, the closer the average will be to 50%

#1063813

I don’t see where yehudayona attributed it to biology.

#1063814
Joseph
Participant

TY T613. Even though you’re at least the fourth person (which is okay since you’re not expected to read every comment) to correct me (on a point that I was aware but slipped my mind – the horror), you did so without throwing in an adjective such as ignorant that a few others felt compelled to make for reasons only known to themselves.

#1063815
cozimjewish
Member

um, was the OP always joseph? Idk why but I thought it was s/o else

#1063816
πRebYidd23
Participant

Lior.

#1063817
frumnotyeshivish
Participant

Lior is Joseph! Mods, you can’t say I didn’t call it. Twice. (Although mods didn’t let one of them through.)

#1063818
cent_cent
Participant

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.

#1063819
πRebYidd23
Participant

and so many pairs of posters just happened to be each other

#1063820
Joseph
Participant

One of the great benefits of being the OP is that everyone reads the OP and responds to it whereas if you post in middle of a thread most folks don’t even look at it and repeat the same point five others already made.

#1063821
ubiquitin
Participant

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

#1063822
Patur Aval Assur
Participant

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%.

#1063823

Was it worth blowing two computers on that?

#1063824
Sam2
Participant

DY: He only blew one. It’s the same math.

#1063825

Oh, then I guess it’s no big deal.

#1063826
charliehall
Participant

“Many Chinese parents manipulate the results by aborting female pregnancies”

This happens in much of India, too.

#1063827
charliehall
Participant

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.

#1063828

It’s Hashem’s way of allowing for a slight age gap.

#1063829
Patur Aval Assur
Participant

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.

#1063830
Joseph
Participant

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. [emphasis added]

Dr. Hall: Do you believe there is a significant amount of abortions in the U.S. specifically targeting female pregnancies? As a biostatistician, do you believe the U.S. birth rate would be near parity if not for unnatural factors?

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