Reversion to the Mean IQ is not the rule.

[Mrdthree]

The theory that smart immigrants from low IQ countries show a propensity to reversion to the mean IQ is inconsistent with the claim that the claim that IQ is 60-80% heritable

 

Problem 1:

If it is assumed  that IQ is 60-80% heritable, then it follows that a smart immigrant is more likely than not smart by virtue of genetics. This means it is unreasonable to assume that an immigrant from a low IQ country is smart by pure environmental causes. This also means it is more likely than not that the intelligence of the immigrant is a heritable trait that will be passed to offspring. These are forces that resist the claim of reversion to mean.

 

Resolving this contradiction is done either by assuming that

(1) IQ is somewhat less than 50% genetic, this would eliminate the bias of inheritance and assure reversion to the mean.

(2) if the premise of >50% heritability is kept then reversion to the mean requires additional assumptions like: smart immigrants tend to mate within their group and to randomly with respect to IQ.

[RichardY]

Isn't the Genetic code a lot of repetition and redundant or vestigial code? 

 

Perhaps like shuffling millions of decks of cards together, one pile from the mother and one from the father, and cutting the deck. Maybe the new hand the child is dealt with will contain a few Aces, but they could be either at the back of the deck and recessive or diluted across a wide genetic code, assuming less inbreeding. More inbreeding might result in more pronounced features maybe even desirable traits, but also a lot of Jokers or not enough variety in the deck to form various features, toes, fingers, brain structure etc.

[Wuzzums]

Let's take a case study.

 

Let's say that a migrant with an IQ of 160 has 10 offspring.

Let's assume 80% of IQ is heritable.

This means there's a pretty good chance that 8 out of 10 of his kids have a very high IQ and the remaining 2 will not.

We also know that the smarter the person is, the fewer children they have. So let's assume that the smart offspring have 1 kid each and the dumb ones 2 kids each.

So in 2 generations, from 1 smart person we ended up with 8 smart people and 4 dumb people.

We move one generation further and we'll end up with 8 new smart people (16 in total now) and 8 new dumb people (12 in total now).

 

What we now see is that if we add in the "dumb people breed more" factor we easily see how they can easily outbreed intelligence only in a matter of a few generations.

 

However, if the 160 IQ migrant comes from a place where the median IQ is 100 then it's more unlikely his offspring will have a lower IQ than 100 thus categorizing them all in the smart 1 offspring category.

Thus the lower the median IQ of the native population, the higher the chance of having dumb offspring.

 

 

This is the algorithm I used to demonstrate why high IQ migrants from a low IQ zone could lower the mean IQ of the new country. Keep in mind I didn't take several factors into consideration like what does it mean exactly to say IQ is 80% heritable? Do the offspring inherent the IQ full stop like eye color? Or do they inherent 80% of the IQ of their parents? What about the 20% non heritable aspect? Doesn't that imply that the offspring which did not inherent any of the smarts be able to get a IQ boost from the environment?

 

There is a lot we don't know about IQ and at this point all we have is data and correlation with no underlying clear mechanism.

[Mrdthree]

Isn't the Genetic code a lot of repetition and redundant or vestigial code? 

 

Perhaps like shuffling millions of decks of cards together, one pile from the mother and one from the father, and cutting the deck. Maybe the new hand the child is dealt with will contain a few Aces, but they could be either at the back of the deck and recessive or diluted across a wide genetic code, assuming less inbreeding. More inbreeding might result in more pronounced features maybe even desirable traits, but also a lot of Jokers or not enough variety in the deck to form various features, toes, fingers, brain structure etc

 

My point is that reversion to the mean or an IQ heritability of 60-80% conflict.

I tend to think the IQ heritability claim is stronger. In which case we need to reasons why it doesnt apply to immigrants.

Your claim may be a valid hypothesis: reversion to the mean occurs because immigrants tend to inbreed and have a higher rate of latent genetic diseases. But is this strong enough to override a trait whose heritability is 60-80%? has it been tested?

[Mrdthree]

Let's take a case study.

 

Let's say that a migrant with an IQ of 160 has 10 offspring.

Let's assume 80% of IQ is heritable.

This means there's a pretty good chance that 8 out of 10 of his kids have a very high IQ and the remaining 2 will not.

We also know that the smarter the person is, the fewer children they have. So let's assume that the smart offspring have 1 kid each and the dumb ones 2 kids each.

So in 2 generations, from 1 smart person we ended up with 8 smart people and 4 dumb people.

We move one generation further and we'll end up with 8 new smart people (16 in total now) and 8 new dumb people (12 in total now).

 

What we now see is that if we add in the "dumb people breed more" factor we easily see how they can easily outbreed intelligence only in a matter of a few generations.

 

However, if the 160 IQ migrant comes from a place where the median IQ is 100 then it's more unlikely his offspring will have a lower IQ than 100 thus categorizing them all in the smart 1 offspring category.

Thus the lower the median IQ of the native population, the higher the chance of having dumb offspring.

 

 

This is the algorithm I used to demonstrate why high IQ migrants from a low IQ zone could lower the mean IQ of the new country. Keep in mind I didn't take several factors into consideration like what does it mean exactly to say IQ is 80% heritable? Do the offspring inherent the IQ full stop like eye color? Or do they inherent 80% of the IQ of their parents? What about the 20% non heritable aspect? Doesn't that imply that the offspring which did not inherent any of the smarts be able to get a IQ boost from the environment?

 

There is a lot we don't know about IQ and at this point all we hative is data and correlation with no underlying clear mechanism.

 

If the number of fertile offspring is inversely proportional to IQ and IQ is 60%-80% heritable, the mean IQ of any breeding pool will collapse. Hence if given a simple literal translation, this algorithm will fail, regardless of initial IQ of the breeding population. In other words, the fitness function with regard to IQ is not a simple inverse linear function.

 

What does the function look like? It probably has an inverted 'U' with IQs below 60 producing few surviving grandchildren and IQs above 180 producing few surviving grandkids (Newton hates everyone).

[RichardY]

Assuming the environment is kept relatively consistent between 2 children wouldn't  approximately 100% of IQ be heritable? To say otherwise would be to suggest some outside factor like a soul? Or... to say that you are determined by your environment and IQ is irrelevant.

 

The children would obviously inherit a  fairly broad genetic base assuming no inbreeding so I guess any high IQ migrants offspring would probably regress to the mean (for their race), though maybe marginally higher given higher IQ parents.

 

Hybrids. I wonder if it possible to produce much higher IQ offspring from lower IQ parents? So you could have one tribe say the Celts of the British Isles, with small round heads but a fairly large amount of brain infolding, fairly peaceful fewer tribal incursions (K selected excluding the occasional wicker man sacrifice). Compared to the Saxons or Vikings with larger more square heads but less brain infolding. If you crossed the two you could have potentially more brain infolding within a larger head size. Maybe you could name the new race or tribe the English or something. I think Steve Jobs, Bruce Lee and Cher are examples of Hybrids. Also I think some of the "large" brain sizes in China has lead to a lot of C sections (50%). 

[Mrdthree]

Assuming the environment is kept relatively consistent between 2 children wouldn't  approximately 100% of IQ be heritable? To say otherwise would be to suggest some outside factor like a soul? Or... to say that you are determined by your environment and IQ is irrelevant.

 

The children would obviously inherit a  fairly broad genetic base assuming no inbreeding so I guess any high IQ migrants offspring would probably regress to the mean (for their race), though maybe marginally higher given higher IQ parents.

 

Hybrids. I wonder if it possible to produce much higher IQ offspring from lower IQ parents? So you could have one tribe say the Celts of the British Isles, with small round heads but a fairly large amount of brain infolding, fairly peaceful fewer tribal incursions (K selected excluding the occasional wicker man sacrifice). Compared to the Saxons or Vikings with larger more square heads but less brain infolding. If you crossed the two you could have potentially more brain infolding within a larger head size. Maybe you could name the new race or tribe the English or something. I think Steve Jobs, Bruce Lee and Cher are examples of Hybrids. Also I think some of the "large" brain sizes in China has lead to a lot of C sections (50%). 

1. Gene expression is a physical process with noise. Even Twins reared together have only 88% correlated IQ http://www.wsj.com/articles/SB10001424052702304898704577478482432277706

2. If IQ is inherited, then children of high IQ parents (regardless of immigrant label) inherit a high IQ.

3. Yes it is possible to make smarter kids from dumber parents suppose four genes make smart. father={smart, dumb,dumb, smart}, mother={dumb, smart dumb dumb}, kid picks 1 gene from each parent and gets={smart, smart, dumb, smart}. or brainfolding...

Let's take a case study.

 

Let's say that a migrant with an IQ of 160 has 10 offspring.

Let's assume 80% of IQ is heritable.

This means there's a pretty good chance that 8 out of 10 of his kids have a very high IQ and the remaining 2 will not.

We also know that the smarter the person is, the fewer children they have. So let's assume that the smart offspring have 1 kid each and the dumb ones 2 kids each.

So in 2 generations, from 1 smart person we ended up with 8 smart people and 4 dumb people.

We move one generation further and we'll end up with 8 new smart people (16 in total now) and 8 new dumb people (12 in total now).

 

What we now see is that if we add in the "dumb people breed more" factor we easily see how they can easily outbreed intelligence only in a matter of a few generations.

 

However, if the 160 IQ migrant comes from a place where the median IQ is 100 then it's more unlikely his offspring will have a lower IQ than 100 thus categorizing them all in the smart 1 offspring category.

Thus the lower the median IQ of the native population, the higher the chance of having dumb offspring.

 

 

This is the algorithm I used to demonstrate why high IQ migrants from a low IQ zone could lower the mean IQ of the new country. Keep in mind I didn't take several factors into consideration like what does it mean exactly to say IQ is 80% heritable? Do the offspring inherent the IQ full stop like eye color? Or do they inherent 80% of the IQ of their parents? What about the 20% non heritable aspect? Doesn't that imply that the offspring which did not inherent any of the smarts be able to get a IQ boost from the environment?

 

There is a lot we don't know about IQ and at this point all we have is data and correlation with no underlying clear mechanism.

 

I think my post was dropped by mediator?

If so response was if dumb people have more reproductive successful (dumb) children then mean IQ will drop regardless of starting point-- i.e. a mean IQ of 100 has to reflect some type of equilibrium.

[RichardY]

1. Gene expression is a physical process with noise. Even Twins reared together have only 88% correlated IQ 

Yes, there is environmental variability both during development and after. Perhaps physical space within the womb the mother's movements, various forms of radiation. But, 88% correlated IQ seems fairly high, If they only had 10% correlation It would make sense that either they had individualistic souls or the Environment was determining them kind of like some clay or voodoo doll. The problem I see is the more you say the environment determines you the less freewill and the less of you as a person you effectively  are saying there is.

 

 

2. If IQ is inherited, then children of high IQ parents (regardless of immigrant label) inherit a high IQ.

 

 

 

I would say you inherit your I.Q but not necessarily the same level or ability of the parents, so you carry the genetics which you may pass on to future offspring. Not that someone would ever do this, but if you had one twin in a box isolated with the bare necessities to maintain breathing and the other had a life of Intellectual stimulation, if you tested them when they were 60 I would imagine the boxed twin would do much better then the free one. However with the dawn of the Internet, the capacity for people to be in contact with one another and information  I would imagine would decrease the environmental effect on IQ. 

 

 

 

3. Yes it is possible to make smarter kids from dumber parents suppose four genes make smart. father={smart, dumb,dumb, smart}, mother={dumb, smart dumb dumb}, kid picks 1 gene from each parent and gets={smart, smart, dumb, smart}. or brainfolding...

 

 

I think the issue is there isn't a smart or dumb gene, but more, like cogs working together in a machine, Brainfolding might be good if it creates the potential for more neural connections, but your also looking at neural transmitters, myelinated cells, blood circulation, heart rate, spinal nerves. Perhaps when your dealing with humans your dealing with a much wider genetic base 3,000,000,000 base pairs vs 130,000 for some bacteria or 5,000 pairs for some viruses any changes or gene expression in the more simpler organisms I would expect a much wider change in the nature of the organism. Something like a human however maybe less of an effect unless it is something absolutely vital, maybe critical organs have duplicate coding to cover potential errors to prevent early death. You can live without hair or fingers, you can't without a heart or brain.

 

 

[Matthew Ed Moran]

Regression to the mean: according to the concept of regression toward the mean, parents whose IQ is at either extreme are more likely to produce offspring with IQ closer to the mean (or average).

 

Since the mean IQ of immigrants who are African, Indian, Arab, or Mestizo is lower than Europeans and Eastern Asians, then any African, Arab, or Mestizo who has an IQ of 100, 115, or 130 is more susceptible to regression to the mean, because their IQ is about a standard deviation lower than Europeans and Asians with a similar placement along the bell curve.

 

In other words, an IQ 100, 115, or 130 African, Indian, Arab, or Mestizo is much more "extreme" on the bell curve compared to their European and East Asian counterparts. If a European couple who both have 130 IQs have kids, their kids are likely to be higher IQ than the children of a 130 IQ Mestizo couple, because the former is two standard deviations away from the mean while the latter is 3 away, and thus much more rare on average.

 

I don't have any clue how what you said relates to regression to the mean problem as it relates to immigration. Regression to the mean is not a concern among Asians, because their mean IQ is not a standard deviation below Europeans, who make up the majority of Americans.

[fstearns1]

Regression to the mean is a statistical phenomenon, and has nothing to do with generational differences. It simply says that when two variables have a correlation coefficient of less than one, using one variable to predict the value of the other, the other will be closer to to the mean. There are several excellent explanations of this phenomenon on YouTube. It is counterintuitive and almost universally misunderstood.

[Matthew Ed Moran]

Regression to the mean is a statistical phenomenon, and has nothing to do with generational differences. It simply says that when two variables have a correlation coefficient of less than one, using one variable to predict the value of the other, the other will be closer to to the mean. There are several excellent explanations of this phenomenon on YouTube. It is counterintuitive and almost universally misunderstood.

 

I'm no expert (to say the least), but I don't think regression to the mean in statistics is the same as regression to the mean in IQ. I think the difference is that regression to the mean in IQ is an observed phenomena.

[fstearns1]

You may be confused about the term 'regression'. Regression analysis has nothing to do with 'reversion'. It is a statistical analysis technique concerning a variety of subjects. Again, see the YouTube articles on the subject for enlightenment.

[ValueOfBrevity]

You may be confused about the term 'regression'. Regression analysis has nothing to do with 'reversion'. It is a statistical analysis technique concerning a variety of subjects. Again, see the YouTube articles on the subject for enlightenment.

 

Perhaps you could link some of those videos and "enlighten" us 

[Matthew Ed Moran]

Perhaps you could link some of those videos and "enlighten" us 

 

It's almost universally misunderstood, yet gives no guidance other than to vaguely suggest somewhere on Youtube is the correct explanation. lol

The theory that smart immigrants from low IQ countries show a propensity to reversion to the mean IQ is inconsistent with the claim that the claim that IQ is 60-80% heritable

 

Problem 1:

If it is assumed  that IQ is 60-80% heritable, then it follows that a smart immigrant is more likely than not smart by virtue of genetics. This means it is unreasonable to assume that an immigrant from a low IQ country is smart by chance. This also means it is more likely than not that the intelligence of the immigrant is a heritable trait that will be passed to offspring. These are forces that resist the claim of reversion to mean.

 

Resolving this contradiction is done either by assuming that

(1) IQ is somewhat less than 50% genetic, this would eliminate the bias of inheritance and assure reversion to the mean.

(2) if the premise of >50% heritability is kept then reversion to the mean requires additional assumptions like: smart immigrants tend to mate within their group and to randomly with respect to IQ.

 

According to Wiki, heritability measures the proportion of variation in a trait that can be attributed to genes, and not the proportion of a trait caused by genes. I'm pretty sure that accounts for your problem. For anyone interested in this subject, a two minute video has an overview and meaty description in the text below the video about what research has found about regression to the mean in IQ. It's called...

 

'IQ & Regression to the Mean - explained by Professor Philippe Rushton'

[fstearns1]

A particularly good explanation of regression to the mean is the YouTube article called "Misunderstanding Regression to the Mean" by Joel Schneider.

[fstearns1]

Also there is a short summary of the concept in Murray and Herrenstein's "The Bell Curve".

[Mrdthree]

A particularly good explanation of regression to the mean is the YouTube article called "Misunderstanding Regression to the Mean" by Joel Schneider.

That clarifies alot. It sounds like it is a process that is true when you do repeated experiments with a random variable that has a convex distribution (two tailed distribution).

A good model might be:

(1) You are given the IQ of one parent.

(2) You pick the IQ of the second parent from the population conditioned on the IQ of the first parent (as per whatever the correlation of parental IQ is-- I suppose this could be a cultural parameter). This would clearly be a case of regression to the mean.

(3) Compute the IQ of the offspring as the average of the two parents. Here the variability could be symmetric as there is no reason to suppose an asymmetric curve here (assumption?) hence the child is uniform noisy reflection of the parental IQ mean.

(4) send offspring to (1).

 

SO lets apply this model to the immigrant case:

 

(1) Suppose there is a native breeding pool with an IQ of 100 mean.

(2) Suppose there is a foreign breeding pool with an IQ of 80 mean.

 

Suppose an immigrant of IQ 130 from the foreign breeding pool (2) enters the native breeding pool (1) and picks a mate from (1).

 

To which mean does his lineage regress? (A) a mean of breeding pool (1)? (B) a mean of breeding pool (2)? or © a weighted mean of breeding pool (1) and pool (2)?

 

According to the model above, one should expect the regression to the mean came from picking a mate and regression to the mean would entail (A)-- a regression to the mean of breeding pool (1).

 

If the immigrant ghettoizes then two possible outcomes can occur depending on whether the immigrants are an isolated breeding pool; (1) suppose immigrants form an isolated breeding pool, then mates will be selected from a distribution that is characteristic of the immigrants in that country and regression to the mean will involve regression to the immigrant community mean. The quality of this mean may depend on immigration laws.

(2) suppose the breeding pool is open, then the emigre population will more closely resemble the foreign breeding pool and regression to the mean will move to case (B).

 

SO I was wrong (correlation does not resist regression to the mean). And I was right-- regression to the mean is not guaranteed-- it depends on the behavior of immigrants and their statistics.

[fstearns1]

Let's discuss a little more.
Suppose you have a scatter graph with the X-axis being the parent's IQ and the Y-axis being the offspring's IQ, and suppose that the correlation is less than 1 and greater than -1. Actually you can use any variables' correlations, not just IQ's. If you choose the parent's IQ as a predictor of offspring's IQ, there will be a regression towards the mean. BUT, if you choose the offspring's IQ as a predictor of the parent's IQ, the parent's IQ will also show a regression to the mean. Again this applies to a static data set, not to generational differences.

 

Let's try a little reductio ad absurdam argument here. If regression to the mean occurs only to the offspring, then selective breeding cannot occur. Clearly this is false. Therefore, the premise is false.

 

I would love to have this discussion directly with Stephan, as I would like to disabuse him of his false understanding of this concept.

[jpc]

I think there are a lot of distributional prior assumptions going into the model. Eg:

 

Assumption 1: there will be a lower -IQ producing genotype and then there will be a say a zero-mean noise distribution around it in phenotype (here measured by IQ).

Assumption 2:

Immigrants are selected on higher phenotype but not genotype.

Assumption 3: Breeding is done based on favourable phenotype (if at all --> well-fare state, advanced medicine) not genotype. 

Then there is selection bias toward the upper end of the phenotype but of course this leaves the genotype's mean unchanged, so their kids will still not have a greater chance of being smart than the rest of the immigrant's home population and, in particular, the expected IQ of the second-generation immigrants will not be greater than the expected IQ of the home population, in spite of the first generation being measurably smarter (cannot see  a contradiction under these assumptions).

 

That aside, I think Stefan's focus on IQ might skew the debate a little. I know he is an IT guy and I am sure for a coder IQ is a good measure of success. But I do not think the same is true for other meaningful professions (eg lawyers, doctors, entrepreneurs (?) etc).

Now, IQ clearly matters if your society needs a lot of Engineers but otherwise not so much I would argue. This is the reason why IQ is such a contrversial quantity and there are multiple competing tests and scales of IQ.

 

By the way: Gossip goes that MIT dismisses standardized tests like the GRE (which correlate with IQ) because of the fact that a lot of their top scientists obtained low score and due to the iffy evidence of their general predictiveness.