sex selection in having kids in AAs

[Shadow_Reaper]

Thanks to fallout central for this:


" Having sons is important to many Asian cultures, and now American families from those groups seem to be asserting the same preference. A new analysis of the 2000 Census shows that among U.S. born children of Chinese, Korean and Asian Indian parents the odds of having a boy increase if the family already has a girl or two.

The findings "suggest that in a sub-population with a traditional son preference, the technologies are being used to generate male births when preceding births are female," co-authors Douglas Almond and Lena Edlund said of their findings, appearing in Tuesday's edition of Proceedings of the National Academy of Sciences.

"We should emphasize that our paper does not imply that sex selection is practiced by all or even most Asian-Americans," they said in an e-mail response to questions. Most Chinese, Korean, and Asian-Indian parents do not sex select.

The discovery that some do, however, seems to be a new development in the United States, since the researchers didn't find the same variance in the 1990 census, Almond, of Columbia University and Edlund of the National Bureau of Economic Research in Cambridge, Mass., reported.

Edlund and Almond said they do not know what method is being used for sex selection, but they speculated that the most common is fetal ultrasound to determine the sex of the baby followed by disproportionate abortion of females. Ultrasound has improved in recent years and is being given earlier, they noted.

"Between 1989 and 1999, prenatal ultrasound use among non-Japanese Asian mothers rose from around 38 percent to 64 percent of pregnancies," they said, citing data from the U.S. National Center for Health Statistics.

The normal sex ratio at birth is 1.05 boys to 1 girl and that holds for first children of these families, the researchers found.

But if the first baby is a girl, the odds of a boy coming next rise to 1.17-to-1, and after two sisters the likelihood of having a son jumps to 1.51-to-1.

High sex ratios in Asia have received considerable attention and Almond and Edlund were curious whether the same could be observed in the United States.

Among the explanations in Asia is China's one-child policy, they noted. "For India, it is often claimed that dowries are necessary to marry off a daughter, while sons are money spinners who can get both a dowry and support the parents in old age," they said.

Carl Haub, a population researcher at the private Population Reference Bureau, said Indians he has studied have a high level of son preference.

"If you are a Hindu it is of great value to have a son officiate at your cremation," explained Haub, who was not part of the research team.

Haub said he was not surprised that some families from Korea, China and India brought their cultural and social values to the United States.

Phil Morgan of Duke University's Center for Social Demography and Ethnography, said he too was not surprised at the finding.

"We see this pattern strongly in places like South Korea. Why would it not show up here? I think that it is unlikely to persist in subsequent generations," added Morgan, who was not part of the research team.

The American College of Obstetricians and Gynecologists and the American Society of Reproductive Medicine say assisting patients in choosing the sex of their offspring to avoid serious sex-linked genetic disorders is ethical, but they discourage sex selection for personal and family reasons, such as family balancing.

Nevertheless, while many countries prohibit sex selection techniques without a medical purpose, the United States does not.

The research was funded by the Institute for Social and Economic Policy Research at Columbia University."

http://www.foxnews.com/story/0,2933,344535,00.html

Funny how to douche bag who made the headlines say something about Asian parents prefer to have sons even though the article is based on the crux of birth ratio of females to males?

God the media just love creating tension between females and males in the AA community dont they?

[SamuraiJack]

I wonder what the preference for white couples are...

[angi]

Acting as if there aren't sex preferences doesn't make the study and less valid. Attack the validity of the study not blast it with knee jerk reactions.

[minbo]

The normal sex ratio at birth is 1.05 boys to 1 girl and that holds for first children of these families, the researchers found.

But if the first baby is a girl, the odds of a boy coming next rise to 1.17-to-1, and after two sisters the likelihood of having a son jumps to 1.51-to-1It is a jump to go from the rates to saying that people are practicing selective sexual selection of their children. I too would like to see "normal" data to compare. Statistically, the ratio of having a boys after having a girl or two girls will be higher than the normal 1.05 to 1, just as I would expect ratio of girls after a boy or two boys would be higher than the 1 to 1.05 as well. If you have two kids, then it is statistically far more likely that it is one boy and one girl rather than two girls or two boys, just as statistically it is far more likely to be two girls and one boy if three children over having three girls.

[SamuraiJack]

Acting as if there aren't sex preferences doesn't make the study and less valid. Attack the validity of the study not blast it with knee jerk reactions.

Sorry, but it is a valid question. If the sexual preference among non-Asian Americans is close to this study, let's say within the margin of error, then the validity of this study is in question. That way we know how much it deviates from "American" culture.

They should also mention the distinction that these couples were born and raised in their respective countries, as well as not using "Asian" and "Chinese/Korean/Indian" interchangeably.

Ultimately, this is a useless study, as they point out:

"We see this pattern strongly in places like South Korea. Why would it not show up here? I think that it is unlikely to persist in subsequent generations," added Morgan, who was not part of the research team.

Well, duh?

[ZhuBaJie]

It is a jump to go from the rates to saying that people are practicing selective sexual selection of their children. I too would like to see "normal" data to compare. Statistically, the ratio of having a boys after having a girl or two girls will be higher than the normal 1.05 to 1, just as I would expect ratio of girls after a boy or two boys would be higher than the 1 to 1.05 as well. If you have two kids, then it is statistically far more likely that it is one boy and one girl rather than two girls or two boys, just as statistically it is far more likely to be two girls and one boy if three children over having three girls.

no it doesn't work like that. every time you have a child, no matter how many children you've had previously, the chance of you having a boy vs. having a girl is still 50/50.

think about if you were flipping a coin. it doesn't matter how many times you've flipped it previously, every time you flip it, the heads-to-tails ratio is still 50/50.

[minbo]

The confusion is understandable, but it does work that way.

While it is intuitive sense that every birth has the same probability for boy vs girl born, the statistical probability does change.

It's like the problem outlined in the curious incident of the dog in the night-time:
You are on a game show on television. On this game show, the idea is to win a car as a prize. The game show host shows you 3 doors. He says that there is a car behind one of the doors and there are goats behind the other two doors. He asks you to pick a door. You pick a door but the door is not opened. The the game show host opens one of the doors you didn't pick to show a goat (because he knows what is behind the doors). Then he says you have one final chance to change your mind before the doors are opened and you get a car or a goat. So he asks you if you want to change your mind and pick the other unopened door instead. What should you do?Intuitively you would think that it does not matter if you stayed with your door or if you switched because it is a 50/50 probability. Mathematically, the probability of picking a door with a car actually is 2/3rds if you change your selection and only 1/3rd if you stick with your door.

I'm not going to type out the equation cause it's hella annoying to explain, so I'll just do the list method, since there are only 6 permutations:

Choose door with car: Stay : Get Car
Choose door with car: Change: Get Goat
Choose door with goat: Stay : Get goat
Choose door with goat: Change: Get car
Choose door with goat: Stay : Get goat
Choose door with goat: Change: Get car

Ratio of car for change 2/3
Ratio of goat for change 1/3
Ratio of car for stay 1/3
Ratio of goat for stay 2/3

The birth ratio is obviously a different mathematical model than the game show problem. I just included the game show model because it is similar in that the actual mathematical probability is far different than the intuitive answer.


If we do use the 50/50 ratio, the statistical outcome is:

1st child: boy 50%; girl 50%
2nd child: 2x boy 25%; boy girl 50%; 2x girl 25%
3rd child: 3x boy 12.5%; 2x boy girl 37.5%; 2x girl boy 37.5%; 3x girl 12.5%

Ergo, if you had a girl, the statistical distribution of a 50/50 ratio means you only have a 25% chance the second child will be a girl. If you had two girls, then the statistical distribution says that you only have a 12.5% chance of having a third girl. Yes, I understand that if you had a girl, the cannot get the 2x boy outcome, but the probability is not on the individual child born, but the probability of the sequence occurring of 2x girl or 3x girl out of the entire range of possible outcomes.

If they had included the standard deviation for their ratio and mentioned how well their measurements to obtain the 1.05 boys to 1 girl born fit a standard deviation curve I could make some conclusions as to if the AA child measurements fit within the standard deviation curve to cause for alarm.

Edit to add:

Just thought of a something else to clarify the confusion succinctly. The odds of having a boy or a girl on any given birth stays at 50% in my chart, which you can see from the progression of 1st child, 2nd and 3rd. The confusion arises because the researchers have changed the global 50% chance to look for a *a special case*. While they phrase their question as "if you have one girl, what is the ratio of boys to girls on the next birth", "if you have two girls, the ratio of boys/girls in the third birth", the actual special case they are looking for as far as probability/statistical modeling is concerned is what is the probability of an outcome of 2x girls in 2x births or 3x girls in 3x children.

If there is no sexual selection in preference of boys, the 1.05 ratio of boys to girls should still hold true if they continue to measure the birth rate as a *general case*, ie. the birth rate of boys to girls across all second births and across all third births, regardless of gender of the earlier children and regardless of the specific outcome of the boy/girl ratio across all the children.

[minbo]

As a followup, if there is a significant issue with improper sexual selection of male children vs female children by the AA society, then it is ridiculously hard to parse from the second, third or whatever ratio of boy/girl for subsequent births. If we had the overall numbers for male children vs female children born for the AA families studied, we could calculate an overall ratio of boy/girl, which when compared to the "normal" boy/girl ratio would quickly and easily show any statistical anomalies outside the standard of error that we may need to be alarmed at.

[jaehwan]

It's like the problem outlined in the curious incident of the dog in the night-time:
Intuitively you would think that it does not matter if you stayed with your door or if you switched because it is a 50/50 probability. Mathematically, the probability of picking a door with a car actually is 2/3rds if you change your selection and only 1/3rd if you stick with your door.

That's the Monte Hall problem, and it throws everyone off!

http://en.wikipedia.org/wiki/Monty_hall_problem

But I think ZBJ is right on this one (see the link above). The Monty Hall problem creates a 2/3 probability of winning only because the host already knows which door holds the goat. So he's throwing it off by using giving you some of his knowledge by showing you a door which he already knows has a goat. If the host were to open a door without knowing whether it was a car or a goat, it would still be 50/50, because he'd be messing up by picking a car 1/3 of the time.

Think about it this way: there's no omniscient game show host when you're having kids.

[ZhuBaJie]

jeebus, this is like Statistics and Probability 101. again, think coin flip. it's the same idea as having a girl vs. a boy.

Intuitively you would think that it does not matter if you stayed with your door or if you switched because it is a 50/50 probability. Mathematically, the probability of picking a door with a car actually is 2/3rds if you change your selection and only 1/3rd if you stick with your door.

yeah you know what, the girl vs. boy problem is a much simpler problem. the reason you have a 2/3 chance of picking the car if you switch is because you have a 2/3 chance of picking a goat on the first door. if the host hadn't opened a door with a goat, your chances of picking the car on your second try remains 1/3 regardless of whether or not you switched. but because the host opens that door, it eliminates a 1/3 chance of picking a goat, thereby increasing you to a 2/3 chance of picking the car.

so if magically, a doctor is able to tell you that if you have sex on a certain set of days, let's say, on every odd days of the month, you'd have a boy. then guess what? your chances of having a girl suddenly increases because you'd avoid having sex on the odd says if you want to have a girl. that's more or less what the host is doing. but the doctor can't actually tell you this, just like what if the host hadn't actually opened that door. so your chances of having a girl remains 50/50, and your chances of picking the car on your second choice remains 1/3.

If we do use the 50/50 ratio, the statistical outcome is:

1st child: boy 50%; girl 50%
2nd child: 2x boy 25%; boy girl 50%; 2x girl 25%
3rd child: 3x boy 12.5%; 2x boy girl 37.5%; 2x girl boy 37.5%; 3x girl 12.5%

Ergo...

wrong.

1st child: boy 50%; girl 50%
2nd child: boy boy 25%; boy girl 25%; girl boy 25%; girl girl 25%
3rd child: boy boy boy 12.5%; boy boy girl 12.5%; boy girl girl 12.5%; girl girl girl 12.5%; girl girl boy 12.5%; girl boy boy 12.5%; boy girl boy 12.5%; girl boy girl 12.5%

your chances of having a boy or a girl, regardless if this is your 2nd, 3rd, 4th, etc., child, remains 50%.

but the probability is not on the individual child born

that's... actually exactly what we're talking about. what is the probably of the individual child born if a couple has already had a girl, two girls, three girls, etc. again, think coin flip. the heads side of the coin doesn't suddenly increase in weight to increase your chances of flipping tails just because you've flipped heads for the last 10 times.

[groinpull]

that's... actually exactly what we're talking about. what is the probably of the individual child born if a couple has already had a girl, two girls, three girls, etc. again, think coin flip. the heads side of the coin doesn't suddenly increase in weight to increase your chances of flipping tails just because you've flipped heads for the last 10 times.

so even though it's the biological norm to have 1.05 boys to 1.0 girls ratio, the chances of having a boy isn't increased after having a girl? That doesn't make sense.

it's like sticking 3 blue marbles and 2 red marbles into a bag. if you pull out a red marble, your chances of pulling out a blue marble are increased. It doesn't always happen, obviously, but the chances of it are increased.

[ZhuBaJie]

so even though it's the biological norm to have 1.05 boys to 1.0 girls ratio, the chances of having a boy isn't increased after having a girl? That doesn't make sense.

it's like sticking 3 blue marbles and 2 red marbles into a bag. if you pull out a red marble, your chances of pulling out a blue marble are increased. It doesn't always happen, obviously, but the chances of it are increased.

again, and again. it's the same as flipping a coin.

your bag of marbles example here doesn't work because parents don't have a set and limited number of children they can have in their lifetime. if a doctor can magically tell you that in your lifetime, you will have 3 boys and 2 girl - and that's it, no more children - then yes, after having a girl, your chances of having a boy would increase.

but let's say you have an infinite number of blue marbles and an infinite number of red marbles in a bag that can hold an infinite number of marbles. you can pull out 10 or 100 red marbles, and the chances of you pulling out a blue marble would still remain 50/50 - because no matter how many red marbles you pull out, there's still an infinite number of them in your bag.

the reason why the natural and unhindered gender ratio is about 50/50 for a population is because for every set of parents that end up having 4 or 5 girls only, there's another set of parents that end up having 4 or 5 boys only.

[minbo]

Yeah, prob & stat 101, what fun... I'll have to go find my books.

Yeah, it should be 25/25/25/25 and 12.5/12.5 etc, but I did a combination rather than permutation and grouped the boy/girl together regardless of which came first.

I do agree that on a simple case of what pops out of the vagina should be the 50/50 (or rather 1.05 to 1 ratio), but I still think that the are looking at their data for a special case of the chance of 2 girls on two births rather than the chance of a girl of a singular birth. I'll re-read the wording of their conclusions a few more times.

[ZhuBaJie]

Yeah, prob & stat 101, what fun... I'll have to go find my books.

Yeah, it should be 25/25/25/25 and 12.5/12.5 etc, but I did a combination rather than permutation and grouped the boy/girl together regardless of which came first.

I do agree that on a simple case of what pops out of the vagina should be the 50/50 (or rather 1.05 to 1 ratio), but I still think that the are looking at their data for a special case of the chance of 2 girls on two births rather than the chance of a girl of a singular birth. I'll re-read the wording of their conclusions a few more times.

well, whatever their wording is, the point is that it doesn't matter if your first child is a boy or a girl, under all normal circumstances, your chances of having a boy or a girl is about 50/50. just because you and all your neighbors are having girls, it doesn't mean you suddenly become more genetically prone to have a boy.

that means they can take a sample of 1000 set of parents whose first children are female, the boy to girl ratio of their second children should, under all normal circumstances, still be 50/50. how does the math work out? because if they take a sample of 1000 set of parents whose first children are male, the boy to girl ratio of their second children should still be 50/50.

[Dirac]

Sex selection is commonly practised in India and by British Indians. Are you doubting this or doubting that it occurs as often as the statistics make out?

[blockthebox]

Speaking of the Monty Hall Problem, here's a recent NYT articles on new research that applies the Monty Hall scenario to suggest that the old cognitive dissonance studies are flawed: http://www.nytimes.com/2008/04/08/science/08tier.html?bl&ex=1207886400&en=7e0160acf86c54ad&ei=5087%0A

[minbo]

OK, so this is a thread from way back. I left off saying that I would read up some more and think about things. I enrolled in an advanced stats course that I am taking now (how is that for OCPD?).

Anyway, I was wrong. I was falling for the false "gamblers fallacy" in trying to apply the law of large numbers to a short run data set and thus thinking that independent variables were somehow dependent.

The data set for "Asian" parents with girls having a second child was 3006 and the data set for The data set for "Asian" parents with girls having a second child was 324. Even so, with the small sample size, the results are between 2 and 3 SD (closer to 3 SD) away from the mean of the independent variable, so the analysis is statistically significant.

Something that was interesting to me was that if the "Asian" parents had one boy, they were slightly more likely than normal for the second child to be a girl. This result however was within 1 SD of the sample measurement and within 1SD of the independent variable, so thus there was simply not enough data to make it statistically significant.

Another interesting statistical anomaly was that the for "Whites", they had 20,682 girl/girl families having a third child, 34,238 girl/boy families and 22,943 boy/boy families, which would give a nice standard curve. For "Asian" parents, they had 324 girl/girl families, 338 girl/boy families and only 241 boy/boy families. It is statistically significant that there were so fewer boy/boy families having a third child vs girl/girl families. One could presume that in the sample set of "Asian" parents with two girls that there are 60 or 80 extra families out of the 324 with a bias to try to have a third kid if they have had two girls. Combined with the results, the 60 to 80 extra families probably are having a third kid because they want a boy. If not all 60 or 80 families succeeded in having a boy, the ratio of boy/girl would effectively normalize.

This outlier behavior to me could be interpreted that while the broader "Asian" American parent population may be statistically similar to gender preference of their children as "White" folks, there is a statistically distinct sub-population of "Asian" parents with a drive to have at least one boy.

With this realization, looking at the data set for families with one girl or one boy having a second child, there are again more families than expected with one girl which is trying for a second child. 3006 one girl to 3095 single boy families. Normal distribution would expect fewer single girl families trying for a second child. I haven't tried to estimate what removing the excess population would do to the boy/girl ratio of the second child, but I suspect that it would be similarly normalizing. The "White" numbers are 139,473g vs 149,103b families.

Lies, damn lies and statistics.