Comments:

1. Can you put the code and data on psyArxiv, github, or a similar public host?

I can link the main meta-analytic code and the effect sizes for dysgenic fertility for intelligence by country

2. I never saw the formula to compute the selection differential. It should be the mean couple-IQ-midpoint weighted by their fertility times h^2. It is also the correlation between fertility and IQ times SD(fertility)/Mean(fertility) times h^2. I think it would be best with both these formulas as you have midpoint and fertility data as well as population parameters for fertility and population IQ fertility correlations.

Added a section at the beginning of the methodology section where I clarify that the formula is the slope divided by the intercept.

3. A table where each row has [Nation/Population, Selection differential, SE of selection differential, number of studies, pooled N] would be nice. 

I added a graph which provides the decline in IQ by decade per nation. The supplement has the meta-analytic model which  contains the standard errors for each country.

4. Another table where each row has [Nation/Population, Corr(IQ, fertility), SE of this, number of studies, pooled N] would be nice. 

The supplement will contain a table of the mean fertility/sd of fertility in each country/data source. Warning - the PISA/PIRLS numbers come from parents only, as the children were tested.

5. Finally if you have mean and sd of fertility by each population a table with that would be nice. You could put this one in an appendix. Same with EA stuff.

6. Scatter plots would be improved by having the r value and the 95% CI of the r value.

The r values are included in the paper, confidence intervals have been shaded in at your request.

7. Also I would either normalize everything or be clearer in table titles / descriptions when stuff has an SD of 15 instead of 1. For example if you are reporting 0.6 per decade it should be clear it is 0.6 points per decade and not 0.6 SDs.

Sure, I will clarify when measurements are standardized or when points are used.

One of your assumptions for the National IQ projections is: "There is no immigration." You then refer to the Pew Research Center's forecast of the United States' racial composition 50 years into the future. However, that projection does include immigration: "Looking ahead, new Pew Research Center U.S. population projections show that if current demographic trends continue, future immigrants and their descendants will be an even bigger source of population growth."

I made that assumption because immigration data for individual European countries is low quality, if not completely missing. For the United States specifically, I attempted to forecast the impact of changes in racial composition because projections and high quality immigration data is available. 

On the basis of current demographic trends, you also state: "The average IQ of the USA is not projected to change substantially based on changes in differences in racial demographics, as the increase in the Hispanic share of the population is offset by the increase in Asians" (p. 17). The problem, here, is not simply that you ignore changes over time in the relative importance of different immigration sources, notably the inevitable decline in immigration from East Asia and the equally inevitable increase in African immigration. You also ignore changes over time within the categories "Hispanic" and "Asian":

- The "Hispanic" category is becoming less Mexican/Puerto Rican/Cuban and more Central American; 

- The "Asian" category is becoming less Chinese/Korean/Japanese and more Filipino and South Asian.

Even if all immigration were to cease tomorrow, there would still be changes over time in the ethnic composition of those two categories, given their age structure. Elderly Asian Americans are largely Chinese, whereas young Asian Americans are much more Filipino and South Asian.

It is doubtful that all immigration will cease tomorrow, either to the US or to any Western country. In fact, the West is moving toward unprecedented levels of immigration. Consequently, the reassuring tone of the conclusion on p. 17 has an air of unreality. At the very least, that sentence should read something like: "Looking ahead, if we assume the immigration levels of 2015 and the continuing dominance of Chinese Americans within the "Asian" category and the continuing dominance of Mexican/Cuban/Puerto Rican Americans within the "Hispanic" category ..."

The paper still states:

"The average IQ of the USA is not projected to change substantially based on changes in differences in racial demographics, as the increase in the Hispanic share of the population is offset by the increase in Asians." (Results)

" However, this study finds that changes in racial demographics are unlikely to have a significant effect on the national IQ of the USA." (Results)

There is 0% probability that either projection will come true. As I stated earlier, the problem is not simply that the immigration intake has considerably changed in recent years, both in volume and in composition. Even if all immigration stopped tomorrow, the "Asian American" category will rapidly change in composition because of the very low fertility among Americans of Chinese, Japanese, and Korean descent.

I suppose it is probably impossible that the effect of changes in racial demographics on national IQ is 0. What really matters is the magnitude.

It isn't enough to tack on a statement that your projections have zero likelihood of being true. Many people skim through academic papers, and they will assume that you stand behind the above statements.

Whether I personally stand by it is not relevant. What is, is that it current evidence does not support the hypothesis that changes in racial demographics will lead to large changes in population IQ within the next 40 years or so. Yes, the categories of "Asian" and "Hispanic" are somewhat heterogeneous in nature and liable to invariance over time, though a rough skim of John's test scores by ethnicity suggests that south east asians/central americans are not that far from their east asian/mexican counterparts in performance. South East Asians score roughly .5 SD lower than NEA, and Hispanics of Central American origin score the same as those of Mexican origin.

The projections that pew center made could potentially be off - I acknowledged that in the paper, and even noted that there have been recent unprecedented increases in central american immigration due to the recent crisis. However, the influx of immigrants from central american countries would truly have to be massive to cause a large decrease in the USA's genotypic IQ. At the moment, the population of the United States is 330 million. To lower the national IQ of the USA from 97 to 96, an increase in 50 million Central American immigrants would be needed. For that to happen, the current border crisis would have to extend until the middle of this century. And I doubt that's going to happen.

https://humanvarieties.org/2023/05/27/iq-scores-by-ethnic-group-in-a-nationally-representative-sample-of-10-year-old-american-children/

https://humanvarieties.org/2023/09/06/sat-act-scores-by-detailed-race-ethnicity-2021/

General:

I recommend improving the paper's grammar with the assistance of ChatGPT. Additionally, consider adding page numbers and line numbers for the convenience of reviewers in locating specific sentences.

Abstract:

"The intensity of dysgenic fertility could vary" -> "The existence and magnitude of dysgenic fertility could vary."

Provide clarity on the absence of fertility and IQ correlation in any country in the abstract.

"National IQ and the selection differential for IQ correlates at 0.51" -> "There is a positive correlation (0.51) between National IQ and the selection differential for IQ."

Noted.

Materials:

"2.6 Excluded studies" -> "Study inclusion criteria."

"A total of 25 studies were excluded from the analyses reported below." -> Where have you said what was included? Can you locate?

The effect sizes, the moderators, and the sources are in the supplement. Everything that could be used (reported a correlation or selection differential, and used a reasonable proxy for cognitive ability), was used, due to the fact that high quality data was not available for most countries.

Discussion:

Consider discussing the potential impact of different national IQs due to environmental factors on international cross-nation dysgenic estimations. Address the possibility that cross-nation heritability for IQ might be much lower than within-population estimations.

I'm not sure whether you mean that the between nation heritability may be lower or whether the heritability within nations may be lower. Regardless, I did discuss the possibility that the heritability within each nation is different (we already know this is the case, as assortative mating for educational attainment differs substantially by country). Latin American and South East Asian countries should have even higher heritabilities for IQ then Europe does, as assortative mating for educational attainment is stronger there.

Note that the Chinese research cited is based on fluid tests, while US tests are based on crystallized ones. Typically, crystallized IQ tests show a more negative correlation with fertility. Therefore, the similar results for China and the US may be unreliable. Chinese IQ is declining more rapidly than in the US and China will have a much lower IQ in the future.

The Chinese effect size comes from a crystalized test. Wang and Fuerst reported selection differentials for both the fluid tests and the crystalized tests.

Address the omission of emigration from Asia in the discussion of immigration to the USA. The article linked (https://www.wsj.com/articles/chinas-brain-drain-threatens-its-future-dbe38096) discusses China's brain drain, which could pose a problem for source countries.

I wanted to avoid discussing immigration as much as possible, because high quality data on immigration is scarce, and there is no guarantee that those immigration patterns will continue in the future. Even within the United States, it is not possible to come to any sort of consensus on the extent to which immigration/emigration flow affects average IQ of the nation.

Regardless, I added a small section which addresses the possibility of brain drain resulting in changes in national IQ in regions like China.

The original submission mentioned "Mutational load is not a factor in decreasing IQ" but not included in the revision. Add a discussion on the natural decline of IQ due to mutation accumulation.

Added.

I am not appointed as a reviewer, and there are already 3 appointed reviewers, so I will simply give a few suggestions. You use the s-factor variable but I would recommend providing a proper context since most readers likely aren't familiar with it and don't know what to expect or whether it's even a reliable variable. For instance, cite papers which use this variable and summarize very briefly the results (e.g., the s-factor correlates). There are many papers but here are ones of the first to have constructed such a factor:

https://openpsych.net/files/papers/Kirkegaard_2014d.pdf
https://openpsych.net/files/papers/Kirkegaard_2014e.pdf

Noted.

In section 2.6, you wrote "A total of 25 studies were excluded from the analyses reported below.". I suggest providing the list of these 25 studies, if not in the main text at least in the supplemental material. Others may be interested in these studies.

For Tables 1 and 5, I suggest reporting how the parameters change across model specifications. I find it odd this step was skipped. And the description of these tables is lackluster.

Noted. Tables have been described in more detail, and the effect of the introduction of moderators has been highlighted in the text as well.

Finally, these authors are missing in the reference section: McClean and Nordsletten.

ty

Replying to Sebastian Jensen

"current evidence does not support the hypothesis that changes in racial demographics will lead to large changes in population IQ within the next 40 years or so"

Let me recapitulate my criticisms of your projection, and its underlying assumptions:

1. For the US, you are using an outdated demographic projection that reflects the immigration intake of 2015 (Pew Research Center). In 2015, immigration was running at about a million a year. Currently, it is running at over three million a year, although no one really knows the exact number.

2. You are ignoring the surge of immigration from new source regions, particularly Africa. Most migrants to Europe are now coming from that continent, and the same will be true for the US and elsewhere. Africa is now where most of the world's population growth is taking place.

3. You are ignoring the immigration shifts within the "Asian" category, as well as the differences in fertility among Asian Americans. In your reply, you state that these differences are minor and not enough to affect your overall conclusion. I submit to you that they are more than enough to affect your overall conclusion, i.e., "changes in racial demographics are unlikely to have a significant effect on the national IQ of the USA." As a side-note, you focus on the shift toward immigration from Southeast Asia. What about immigration from South Asia, particularly high-fertility Muslim countries like Pakistan and Afghanistan?

In this kind of situation, it would be best to run several projections with different assumptions:

Projection 1:  (a) immigration will soon fall to 2015 levels of one million a year; (b) geographic origin of immigrants will remain substantially the same (in particular, immigration from Africa will remain low); (c) level of fertility among East Asian immigrants will soon increase to the level of fertility we see among Muslim immigrants from Asia.

Projection 2: (a) immigration will fall to two million a year; (b) geographic origin of immigrants will shift toward African sources (40% of intake); (c) level of fertility among East Asian immigrants will remain at about 1 child per woman; Muslim fertility will fall to 2 children per woman.

Projection 3: (a) immigration will continue at 3 million a year; (b) geographic origin of immigrants will shift toward African sources (70% of intake); (c) level of fertility among East Asian immigrants will continue to fall to about half a child per woman; Muslim fertility will be 3 children per woman.

Which projection is the least realistic? To answer that question, it's important to spell out the underlying assumptions. In my opinion, the first projection is based on the least realistic assumptions, but what do I know?

Replying to Thu 07 Dec 2023 12:44

The paper still states:

"The average IQ of the USA is not projected to change substantially based on changes in differences in racial demographics, as the increase in the Hispanic share of the population is offset by the increase in Asians." (Results)

" However, this study finds that changes in racial demographics are unlikely to have a significant effect on the national IQ of the USA." (Results)

There is 0% probability that either projection will come true. As I stated earlier, the problem is not simply that the immigration intake has considerably changed in recent years, both in volume and in composition. Even if all immigration stopped tomorrow, the "Asian American" category will rapidly change in composition because of the very low fertility among Americans of Chinese, Japanese, and Korean descent.

I suppose it is probably impossible that the effect of changes in racial demographics on national IQ is 0. What really matters is the magnitude.

It isn't enough to tack on a statement that your projections have zero likelihood of being true. Many people skim through academic papers, and they will assume that you stand behind the above statements.

Whether I personally stand by it is not relevant. What is, is that it current evidence does not support the hypothesis that changes in racial demographics will lead to large changes in population IQ within the next 40 years or so. Yes, the categories of "Asian" and "Hispanic" are somewhat heterogeneous in nature and liable to invariance over time, though a rough skim of John's test scores by ethnicity suggests that south east asians/central americans are not that far from their east asian/mexican counterparts in performance. South East Asians score roughly .5 SD lower than NEA, and Hispanics of Central American origin score the same as those of Mexican origin.

The projections that pew center made could potentially be off - I acknowledged that in the paper, and even noted that there have been recent unprecedented increases in central american immigration due to the recent crisis. However, the influx of immigrants from central american countries would truly have to be massive to cause a large decrease in the USA's genotypic IQ. At the moment, the population of the United States is 330 million. To lower the national IQ of the USA from 97 to 96, an increase in 50 million Central American immigrants would be needed. For that to happen, the current border crisis would have to extend until the middle of this century. And I doubt that's going to happen.

https://humanvarieties.org/2023/05/27/iq-scores-by-ethnic-group-in-a-nationally-representative-sample-of-10-year-old-american-children/

https://humanvarieties.org/2023/09/06/sat-act-scores-by-detailed-race-ethnicity-2021/

 

Replying to Sebastian Jensen

It is unlikely that immigration inflows that occur under an incompetent administration right after a global pandemic generalize to the rest of the Century

We are seeing the same dramatic rise in immigration in Canada and the United Kingdom. This is not a "blip" due to the pandemic or an aging president. It reflects an ideological shift in policy-making, specifically a desire to use population growth as a means to drive GDP growth (even at the expense of a decline in GDP per capita). It is uncertain whether this policy will continue, but that is all the more reason why you should use a series of projections with different assumptions.

My position remains unchanged.  The problems with this paper are fundamental and cannot be resolved by adding a vague caveat that the average reader won't notice.

For the US, you are using an outdated demographic projection that reflects the immigration intake of 2015 (Pew Research Center). In 2015, immigration was running at about a million a year. Currently, it is running at over three million a year, although no one really knows the exact number.

It is unlikely that immigration inflows that occur under an incompetent administration right after a global pandemic generalize to the rest of the Century. The amount of immigration anticipated to occur in the next 40 years is probably going to be higher than expected, but difficult to quantify.

You are ignoring the surge of immigration from new source regions, particularly Africa. Most migrants to Europe are now coming from that continent, and the same will be true for the US and elsewhere. Africa is now where most of the world's population growth is taking place.

The magnitude of this increase is unpredictable.

There is, of course, a great deal of uncertainty that comes with projecting the effect that immigration will have on the average IQ of the United States. The degree to which African and European immigrants are selected for intelligence is not accounted for in our models at all. Historically, the immigration policy of the United States has fluctuated frequently with time, and it is probable that this trend will continue in the future, though it is unknown what effect this probable change will have on trends in intelligence.

...

I have now changed the description of the results to "The average IQ of the USA is not projected to change substantially due to fluctuations in racial demographics based on our models." and the description in the discussion to "However, this study finds that changes in racial demographics in the next 40 years will not result in large changes to national IQ based on our models." Note that I do not mention this analysis in the abstract, so a reader will have to read the body of the paper to know that I attempted to project the effect of changes in racial demographics to changes in national intelligence, and I discuss the limitations of these projections in the discussion section.

Replying to Sebastian Jensen

It is unlikely that immigration inflows that occur under an incompetent administration right after a global pandemic generalize to the rest of the Century

We are seeing the same dramatic rise in immigration in Canada and the United Kingdom. This is not a "blip" due to the pandemic or an aging president. It reflects an ideological shift in policy-making, specifically a desire to use population growth as a means to drive GDP growth (even at the expense of a decline in GDP per capita). It is uncertain whether this policy will continue, but that is all the more reason why you should use a series of projections with different assumptions.

My position remains unchanged.  The problems with this paper are fundamental and cannot be resolved by adding a vague caveat that the average reader won't notice.

For the US, you are using an outdated demographic projection that reflects the immigration intake of 2015 (Pew Research Center). In 2015, immigration was running at about a million a year. Currently, it is running at over three million a year, although no one really knows the exact number.

It is unlikely that immigration inflows that occur under an incompetent administration right after a global pandemic generalize to the rest of the Century. The amount of immigration anticipated to occur in the next 40 years is probably going to be higher than expected, but difficult to quantify.

You are ignoring the surge of immigration from new source regions, particularly Africa. Most migrants to Europe are now coming from that continent, and the same will be true for the US and elsewhere. Africa is now where most of the world's population growth is taking place.

The magnitude of this increase is unpredictable.

There is, of course, a great deal of uncertainty that comes with projecting the effect that immigration will have on the average IQ of the United States. The degree to which African and European immigrants are selected for intelligence is not accounted for in our models at all. Historically, the immigration policy of the United States has fluctuated frequently with time, and it is probable that this trend will continue in the future, though it is unknown what effect this probable change will have on trends in intelligence.

...

I have now changed the description of the results to "The average IQ of the USA is not projected to change substantially due to fluctuations in racial demographics based on our models." and the description in the discussion to "However, this study finds that changes in racial demographics in the next 40 years will not result in large changes to national IQ based on our models." Note that I do not mention this analysis in the abstract, so a reader will have to read the body of the paper to know that I attempted to project the effect of changes in racial demographics to changes in national intelligence, and I discuss the limitations of these projections in the discussion section.