Race and IQ -

Moral_Equivalent_of_ISIS

As bad as ISIS if not worse.
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@Shield Breaker I completely agree with about 95% of your statement above, particularly the part about IQ and nurture over nature.


On the neighbors thing, true, immigrants from Africa are a completely different animal than American blacks, but I personally wouldn't single out Pollacks in mobile homes, in the majority of instances I'd choose not to live near any race in mobile homes. It has nothing to do with their ethnic background/race and everything to do with their lifestyle and class. There are trailer parks entirely made up of the same group: blacks, latinos, Asians, and Whites and I wouldn't want to live around any of them if given the choice.

It all goes back to class, which is a much better identifier of a person's attitude and outlook than race. That's not to say wealth makes you a nicer person, however in my experience you're much more likely to have issues with them than most middle class and above neighbors who mind their own business. For instance, no matter the race, if you live in a poor area you're gonna see a lot more alcoholism, drug abuse, fighting, unwed mothers, rotten and violent children and teens, etc. They're gonna be much more miserable to live around than even lower middle class families IMO.

True, but even the ones who are like us typically have relatives and friends who are "into" that whole ghetto culture thing. So it's not like they aren't familiar, they just don't base their entire lives around it. Another thing, they can be really good neighbors but on the whole they don't like us nor do they want to have any more to do with us than absolutely necessary. They will smile in your face and the minute you walk away they'll trash you for the silliest things for no good reason because many of them are just like that. They have this attitude where they think you'd be the same way towards them even if you're not that type of person. They think we're all stuck up even if they have just about as much wealth as we do, simply because we're white. To them, we're no different than rich people who look down and shit on everybody, including their own people, for not being as well-off as them. That's something I've always noticed, we're stuck up and think we're better even when we're not, even when that's the farthest thing from the way you actually carry yourself.

For sure, definitely agree with that. But, there are still differences culturally in the way we all act. Even if they're middle class, somewhat educated, and overall pretty decent people, I've noticed that black people on the whole are a lot more paranoid and superstitious than white people. And I'm not talking about reasonable paranoia that comes from an honest, reasonable place, I'm talking about silly stuff. They'll believe these completely insane, urban legend type stories and spread them around as if they were true and happened to someone they know personally. I've witnessed this in regular people, not ghetto or poor ones with no education. One thing in particular I remember that was a big deal in that community at one point, was that a popular fashion designer who made clothes that a lot of them really liked at the time. All of a sudden, people were saying that this guy was a racist and he didn't want blacks wearing his clothes. This was a huge story at one point in time. I remember asking a black broad what the designer did that was racist and she naturally brought up the interview where he announced that blacks shouldn't buy his clothing. Of course, she didn't actually see this interview, but she heard about it from numerous trusted sources that in the interview this guy said that he didn't like seeing blacks wearing his designer clothes. I kinda convinced her that was stupid, that nobody in the business of selling a product is going to say something ultra controversial about his main customer base, and she reluctantly agreed. But then she said some nonsense about "look at the tv commercials, they always have black people doing something ignorant in them".

I swear to God, I don't think this particular clothes designer even ran television advertisements.

That's all I'm trying to say. They're not stupid people, or bad people, but they do think differently. And for the most part, they aren't ever going to think very highly of us. They're not going to "have our backs" in the way you'd want a neighbor to have your back and look out for your shared community's best interests. That's why I say I'd rather live around people who look like me. I feel like on the whole, they're going to relate to me and sympathize in a way that someone different never would.


No, probably not. As long as it was just one wealthy black family moving in. I think they might get some type of weird satisfaction out of that actually, they could brag to their cosmopolitan friends about their progressive, rainbow coalition community where rich people live in complete harmony, blacks included. Rich Asians and Indians are old hat at this point, and probably wouldn't impress that circle.


Yeah, I'm familiar with the argument of "gentrification" and I don't really agree with it. The demographics of cities change over time, and while I loathe hipsters as much as the next person and would cherish having another reason to dislike them, I don't hate them for wanting to live in "hip" urban areas in various cities. They don't mind living among some of the old black residents of these neighborhoods, but that isn't the draw for them. They like these areas because they are in the middle of a crowded city, where they have access to public transportation, historical restaurants, bar rooms, night clubs, art galleries, etc. All the nice advantages and benefits of living in the big city. I sympathize with the older residents who suddenly have high taxes, but this is solely the fault of the actual city government, not the hipsters who move there.

The politicians in these cities that are experiencing so-called "gentrification", the bottom feeding scumbags that they are, will use the influx of wealthy residents buying property in these blighted neighborhoods as an excuse to raise taxes across the board. The hipsters can usually afford the higher taxes and will see the expense as worth it, the price of living in such a cool area with access to the entertainment and culture they desire. The old residents, who are often elderly as well, get stuck with the higher taxes while being on a fixed income, and they don't give a shit about the culture, the restaurants, the art galleries, etc. close by, they just live there and wanna keep living there because it's what they've already been doing for awhile.

So yeah, I feel for elderly people on a fixed income who have to deal with higher taxes all of a sudden, but I'm not angry that wealthy white people are starting to move back to the inner cities where their parents, grandparents, great grandparents etc. probably lived back in the day before the inner cities starting going to hell, with high crime and blight. And remember, these poor, persecuted minorities that activists claim to be fighting for out of this belief they have some kind of entitlement to these areas because they might've lived there for awhile, don't really have any special connection to these areas as they claim. They act like these are communities that go back for several generations, with a vast historical connection to the neighborhood. That's complete nonsense. Most of these areas were white ethnic communities: Italian, Irish, German, French, etc. until the 1960s and 70s, a lot of time even all the way up until the 1980s. Why aren't they supporting the new generation's desire to return to the inner city? They're merely returning to their roots and reestablishing the old communities their immigrant great grandparents were forced out of by greedy, corrupt politicians who allowed crime and vice to flourish. Why don't these community activist types encourage the "victims" of gentrification to just leave the city and settle in a more affordable suburb? Couldn't they still have a sense of community somewhere else?

Let's face it, you only really hear about "gentrification" being a problem when it's blacks getting "driven out of their homes" by these uncaring, "shallow white hipsters". Even though it happens just as often to old white people who live in the city, we never hear the outrage from community activist types when it's happening to them. Only when it happens to blacks do we even hear about this and are told that the politicians must do something to prevent it somehow, even though there's not much they can legally do (and they wouldn't want to even if they could because all they care about is potential dollar signs).

My grandmother, my father's mother, lived in one of the only neighborhoods in the entire city that is basically 100% white. She lived their her entire life. It was a blue collar neighborhood back in the day, nothing fancy, but as the city changed, demographics changed, people moved around, etc. All of a sudden, a big flood happens, the water level rises, and the many canals that run throughout the region start to overflow, some even start to burst, washing away probably 75% of the homes there. A lot of the elderly residents who lived there for most of a century rebuild their homes. A lot of them also sell their property and leave. A few years pass and all of a sudden there is a renewed interest to live in the city. A neighborhood that's 100% white but still close to all the convenience of the inner city is looking very attractive to buyers. Large homes get built on lots still empty from the flood. My grandmother's street remains mostly the same because somehow many of the original homes were salvageable. More years go by and the city sends assessors in to determine the value of the homes in that neighborhood. They value her home about 200k above the current value, which was about 150k over the actual value that someone in their right mind would ever pay for her tiny, 2 bedroom home. Her taxes increase by a ridiculous amount, based on that bogus assessment which overvalued all of those people's properties. She was never wealthy, but all of a sudden the politicians and the city government decide that she must be taxed like she is.

Is that fair? Of course not. Is it shitty? It's absolutely shitty. But that's the type of cons that these disgusting, bottom feeding politicians pull. You won't ever hear about something like that on the news. It's not titillating or controversial enough to attract the attention of anyone who isn't personally affected by it. But when it comes to gentrification, the kind I talked about prior, where it's minorities leaving an area in droves for the exact situation that happened to my grandma, suddenly people care. It has nothing to do with them, but they care. Whatever media outlet presented the issue to them framed it in such a way that it sounded like just another instance of rich, evil white pushing around innocent minorities, so now people start paying attention. Everybody is familiar with the gentrification issue for that reason only. Cities are always changing, this isn't anything new or special. When an urban area starts filling up with a new crop of greasy hipsters, they need to mind their own goddamn business lol. Stop pretending like you care about some geriatric stranger's tax rate.
I wasn't suggesting gentrification is a problem nor that gentrification is proof that living amongst black people is the exclusive goal of multicultural whites. In my opinion 'gentrification' of black or white people is just an irrational reaction to natural market forces. People move into attractive areas and the prices go up. It's just a result of scarcity and value, not evil. I was just trying to point out that plenty of people find it acceptable for other races to immigrate (and also) find it acceptable to live amongst other races personally. You seem to have shifted away from your original point that white people don't want to live near black people, because they are black. In your original post you said:

Would you rather live in an area that is all white or an area that is all black. Which would you choose? If you're being honest, I already know your answer.

The thing is, every ethnic group who is raising a family is going to choose the white area over the black if those are their choices. Even black families would rather the white area, in fact, them in particular, especially if they spent any time in a majority black environment.
So I was responding to that claim specifically. Even if white hipsters are moving in because "They like these areas because they are in the middle of a crowded city, where they have access to public transportation, historical restaurants, bar rooms, night clubs, art galleries, etc. All the nice advantages and benefits of living in the big city." (which I agree with) doesn't that prove they aren't choosing to avoid black neighborhoods? Clearly race and ethnicity aren't a dealbreaker for pro-multicultural whites, right?


The conversation seems to have shifted considerably from race and IQ to race and segregation.
 
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Yeah but that's an article about a minority being smarter, and therefore won't immediately end the author's academic career. But I can't find any work about comparison with the african-american demographic and in general the use of IQ tests seems to disappear around 2010 despite the data being probably more easy to gather than ever.
The interesting question is whether research was done and thrown away because the results were "incorrect", or that universities don't even attempt to research it because fear of journo feedback.
 
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Lemmingwise

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Yeah but that's an article about a minority being smarter, and therefore won't immediately end the author's academic career. But I can't find any work about comparison with the african-american demographic and in general the use of IQ tests seems to disappear around 2010 despite the data being probably more easy to gather than ever.
The interesting question is whether research was done and thrown away because the results were "incorrect", or that universities don't even attempt to research it because fear of journo feedback.
If a minority can be smarter, it means there can be differences between genetic groups. I don't think anyone will deny that therebis a taboo on the subject.

If you watch the subtitled norse documentary "hjernevask" episode about race, you can see an interview with the earlier mentioned Cochran. You can see how much he is walking on eggshells.

If you want my opinion, he knew that the only way he could do a study on race & IQ if a specific certain group would come out positive. I'm not suggesting to doubt his research, although some do, I'm suggesting he didn't want to go the way of Watson or Charles Murray, so he did an IQ race study that wouldn't get him labeled as a eugenic white nationalist by the SPLC, which is run by jèws.
 

PowerWomon

Kiwi Farm's Most Hated Feminist
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An amazing amount of disinformation and FUD about IQ in this topic from all sides of the debate.
Yes, and it's the same arguments nearly every time. I do not know if that is because of particular strains of misinformation being out there or because people's intuition about the issue leads them down instinctive paths of reasoning. Your post is great and covers pretty much the whole gamut of issues typically brought up with IQ, so I will try to keep what could perhaps be added short.

(This post turned out long after all. Sorry.)

These seem to be the most common questions that come up:
1.) How can you express something as complex as intelligence in a single number?
2.) Why do measures over such large populations matter when we only directly deal with individuals?
3.) Why does intelligence matter if there are so many individuals that are more successful than many with higher IQ?
4.) How can we measure something so fundamental about the brain when we still understand so little about it?
5.) IQ is just an arbitrarily defined metric - how can it tell us anything meaningful or be used to compare people?


This post already turned out long, on an older thread, so I’ll only try to answer 1.) primarily. Answers to the others can probably be inferred from parts.

How can you express something as complex as intelligence in a single number?
I do not think we should find this surprising. There are far more complex things that we summarize into a single or a few numbers. And that number does not fall from the sky, either, or is an oversimplification because it is a single number. It is a summary of a variety of complex tasks. You mention WAIS and WISC already, so everybody is free to look up the kind of tests being used:


(I do not have a better link to a free download as the full manual, from official sources, is about $250. There are several scribd downloaders that can grab the whole file.)

An intuitive way one can think of IQ scores is to liken it to a benchmark for a computer, perhaps (I am aware, though, that this analogy will probably break down if over-stretched and humans cannot be assembled from modular components like PCs). How would you go about comparing the speed of different PC configurations, as there are a huge number of possible combinations and hardware around? What tests would you use for comparison, as you cannot possibly test all available software in existence?

What you would likely do is run a few programs that are particularly representative of a particular performance aspect, such as floating point arithmetic, memory throughput, storage and so forth. Those scores you then summarize into a number for comparison. The underlying system is still very complex and there might be many aspects you do not understand about modern architectures, such as pipelining, hyper-threading, branch prediction, etc. but your goal is to abstract from all these details.

Your friends might now ask: “How can you possibly measure something as complex as computer with a single performance score?” What would you do to convince them of the usefulness of your score is how well it predicts what you are interested in, i.e. how fast their games run, in terms of FPS, perhaps. You can see how good your score is by how well it correlates with what you wish to predict. It does not matter, for the most part, that you are not an engineer at Intel who can design a modern RISC CPU from ground up. If you were to test a car, it sure helps to know a little about cars, but you do not need to be able to build an engine to perform meaningful tests on cars.

You still express a whole bunch of complexity in a single number. I see a lot of references to statistics in this thread, so I am surprised there is so much pushback against a concept that is practically just a factor analysis. It does not matter that you get a single number or a few factors in the end. What matters is how well that set of factors correlates to the metric you are interested in, how much of the variation the set of factors predict. What we are interested in, cognitive performance on g-loaded tasks, is very well correlated, based on available studies. This has been alluded to already and it is what is often referred to as the observation that performance on particular tasks is on a so-called “positive manifold", and, according to Spearman's hypothesis, can be expressed as the g-factor, i.e. if you are better than someone else on one g-loaded task you are likely to also be better on all g-loaded tasks.

Spearman, Charles. “‘ General Intelligence,’ Objectively Determined and Measured.” The American Journal of Psychology 15, no. 2 (1904): 201–292.

What the g-factor might represent is something like a metric how well your brain works. That would be consistent with IQ even strongly correlating with factors that seem to have nothing to do with intelligence at all, such as the already mentioned reaction speed, but also color acuity. The higher your IQ, the higher your color acuity typically is (r=-0.68, between total error score and verbal IQ):

Cranwell, Matthew B., Bradley Pearce, Camilla Loveridge, and Anya C. Hurlbert. “Performance on the Farnsworth-Munsell 100-Hue Test Is Significantly Related to Nonverbal IQ.” Investigative Ophthalmology & Visual Science 56, no. 5 (2015): 3171–3178.

Woodley of Menie, Michael A., and Heitor B. F. Fernandes. “Showing Their True Colours: Possible Secular Declines and a Jensen Effect on Colour Acuity — More Evidence for the Weaker Variant of Spearman’s Other Hypothesis.” Personality and Individual Differences 88 (January 1, 2016): 280–84. https://doi.org/10.1016/j.paid.2015.09.009.


Take an example test here: https://www.colormunki.com/game/huetest_kiosk

(It’s probably not perfect because a bad screen can give you an unfair disadvantage. Obviously, if there is something wrong with your vision, this would not be a good metric, either.)

But here is where the confusion sets in: this applies to g-loaded tasks. There are many tasks that might require huge amounts of memorization (some memorization abilities do correlate with IQ) or some that are not g-loaded, but which we commonly associate with "being smart", where aspects of endurance, motivation, and character are more decisive than your IQ. But that is not a shortcoming of IQ, that is a misunderstanding of what constitutes intelligence, or what we mean by the word in different contexts. Chess, for example, is apparently less g-loaded than often portrayed in popular culture, so, even though it's an advantage to be more intelligent in chess, other factors, possibly related to personality, might outweigh pure IQ differences.

There is also misunderstanding how much IQ must have some direct biological correlate in order to be useful or valid, which is sort of expressed when asking how we can measure when so much of the brain’s structure remains unexplored. In order for a construct to be valid (referred to as “construct validity”), however, it does not mean that IQ cannot simply be a purely psychometric artifact. In principal component analysis, for example, a mix of features that correspond to the original aspects being measured can be subsumed in a single eigenvector and that eigenvector has a corresponding eigenvalue, which roughly speaking corresponds to the contribution the component makes to the overall variance of the underlying data. But the principal component itself might be largely meaningless (from the perspective of being interpretable as a directly observable aspect of the object measured) and have no intuitive unit associated if taken as a metric, like mile, pressure, or weight. But depending on how much variance of the data it predicts, it can tell you how good of a measure it would be if it stood in for the original data. The eigenvalue can be a completely arbitrary number (technically it need not even be normalized I think), yet, it is dismissive to just say that it is an oversimplification of a complex system because we chose to express a highly predictive and representative aspect as a single number.

Examples to play with yourself:

https://wilkelab.org/classes/SDS348/2016_spring/worksheets/class9.html
https://stats.idre.ucla.edu/r/dae/canonical-correlation-analysis/

1591449981798.png
1591447943317.png

I am only using PCA as an example, not making a statement about how appropriate it would or would not be for FSIQ in WAIS, WISC, etc. Similar illustrations could probably be made with canonical correlation analysis (CCA) and other methods of factor analysis or construct validation. But it also illustrates that there is room for other factors, where Big Five Personality (NEO, MMPI, etc.) might come in. You can test that by looking at how much variance is explained by your model, how much these additional factors add to the predictive accuracy of your model.

Last but not least, why should we expect there to be a single factor of general intelligence in the first place? That is actually a question that people who defend the use of IQ do not explain well. In fact, there is no good reason to simply assume that and studies on animal intelligence have actually shown that some species might show a much stronger clustering of abilities. Spearman’s hypothesis might not apply universally. Chimpanzees, for example, might have such a clustering. Mice, on the other hand, appear to have general factor of intelligence similar to humans and it seems to explain a similar size of variance in cognitive performance.

I did not go into the basics of distributions. There are many people, even policy makers, who either pretend to or do not understand that a statement about a group or statistic does not allow one to make direct determinations about individuals. But here is a calculation example:

Assume that a population has a mean IQ of 85 with a standard deviation of 15. That would mean that (1-pnorm(120,85,15))*100 ≈ 0.98% of such a population would have an IQ above 120 (use the cumulative distribution function of the Gaussian distribution and subtract it from 1.0 to obtain the portion above the upper limit of the integral). If you had a population of a million, there would still be about ten thousand such individuals. Some R code for that here: https://ideone.com/EtxYKl.

Another frequent question is to ask why any of that is useful for dealing with individuals. It is not. But we do not exclusively deal with individuals. That is like asking why statistics or sociology are of relevance. When you deal with groups of people, you use a level of analysis that is appropriate for groups. When you deal with an individual, you use a level of analysis that is appropriate for individuals. For example, if you were to design a seat for a car, complete with seatbelt, it would be useful to know how potential drivers are distributed according to weight and height. You would be interested in such statistics as mean weight/height, standard deviation/variance, and p-values of a given confidence interval to be reasonably sure your car is safe. When you have someone come in for an interview, it would be silly to pull out population statistics of the town they were born in. You would use metrics that are more applicable to an individual, such as academic achievement, university attended, years of experience and so forth. But that does not mean statistics are unimportant. Far too often are they misused and any difference in (statistical) outcome is used as evidence for discrimination. For that reason alone it would be good for us to accept population differences in IQ, if there are such differences, and stop chalking up every disparity to evil racists.

And because it is a distribution there are naturally also outliers like Kim Peek, who was able to perform incredible feats of memorization but does not measure very high on IQ tests, consistent with his general difficulty to navigate common life situations autonomously: https://www.youtube.com/watch?v=36K1HQvUdWg

But outliers are not evidence that statistics is wrong, nor is it evidence that it's not useful. It can also certainly be unfair to an invidividual. Work some time at an insurance company. Some teenagers might be perfectly safe drivers, but if you have a large population of people, it is in your financial interest as an insurance company to do a good job on estimating the probability that a given driver, absent of a long driving record, is going to get into a car accident you might have to pay out for.


Matzel, Louis D., and Stefan Kolata. "Selective attention, working memory, and animal intelligence." Neuroscience & Biobehavioral Reviews 34, no. 1 (2010): 23-30.

Deary, Ian J., Steve Strand, Pauline Smith, and C. P. D. Fernandes. “Intelligence and Educational Achievement,” 2007. https://doi.org/10.1016/j.intell.2006.02.001.

Reynolds, Matthew R. “Interpreting the g Loadings of Intelligence Test Composite Scores in Light of Spearman’s Law of Diminishing Returns.” School Psychology Quarterly 28, no. 1 (2013): 63–76. https://doi.org/10.1037/spq0000013.

Rushton, J. Philippe. “The ‘Jensen Effect’ and the ‘Spearman-Jensen Hypothesis’ of Black-White IQ Differences.” Intelligence 26, no. 3 (1998 ): 217–225.
 
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2al

kiwifarms.net
https://www.reddit.com/r/race/comments/9dq0kk/im_starting_to_disassociate_myself_from_my_race/ While I do agree with everyone else in that thread that she is just torturing herself with social anxiety, are the contents of her social anxiety thoughts particularly inaccurate?

''I think you've misunderstood what I'm saying. My point was that anti-intellectualism is just as much of a problem among white people, but it's never discussed in racialized terms. Problems that exist among white people in this country almost never are. White people get to be individuals who aren't defined by a racial category, and it's completely unfair.''
I get the impression that it's worse among black people, sad to say. All the people on A&N are pretty convincing with their articles and statistics and stuff. I'm far away from anywhere with any substantial black community, and this is the impression I get. While I still don't agree with racism, I now get it. When communities fail to police their own, you get people who otherwise wouldn't become racist becoming racist.
 

Lemmingwise

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Yes, and it's the same arguments nearly every time. I do not know if that is because of particular strains of misinformation being out there or because people's intuition about the issue leads them down instinctive paths of reasoning. Your post is great and covers pretty much the whole gamut of issues typically brought up with IQ, so I will try to keep what could perhaps be added short.

(This post turned out long after all. Sorry.)

These seem to be the most common questions that come up:
1.) How can you express something as complex as intelligence in a single number?
2.) Why do measures over such large populations matter when we only directly deal with individuals?
3.) Why does intelligence matter if there are so many individuals that are more successful than many with higher IQ?
4.) How can we measure something so fundamental about the brain when we still understand so little about it?
5.) IQ is just an arbitrarily defined metric - how can it tell us anything meaningful or be used to compare people?


This post already turned out long, on an older thread, so I’ll only try to answer 1.) primarily. Answers to the others can probably be inferred from parts.

How can you express something as complex as intelligence in a single number?
I do not think we should find this surprising. There are far more complex things that we summarize into a single or a few numbers. And that number does not fall from the sky, either, or is an oversimplification because it is a single number. It is a summary of a variety of complex tasks. You mention WAIS and WISC already, so everybody is free to look up the kind of tests being used:


(I do not have a better link to a free download as the full manual, from official sources, is about $250. There are several scribd downloaders that can grab the whole file.)

An intuitive way one can think of IQ scores is to liken it to a benchmark for a computer, perhaps (I am aware, though, that this analogy will probably break down if over-stretched and humans cannot be assembled from modular components like PCs). How would you go about comparing the speed of different PC configurations, as there are a huge number of possible combinations and hardware around? What tests would you use for comparison, as you cannot possibly test all available software in existence?

What you would likely do is run a few programs that are particularly representative of a particular performance aspect, such as floating point arithmetic, memory throughput, storage and so forth. Those scores you then summarize into a number for comparison. The underlying system is still very complex and there might be many aspects you do not understand about modern architectures, such as pipelining, hyper-threading, branch prediction, etc. but your goal is to abstract from all these details.

Your friends might now ask: “How can you possibly measure something as complex as computer with a single performance score?” What would you do to convince them of the usefulness of your score is how well it predicts what you are interested in, i.e. how fast their games run, in terms of FPS, perhaps. You can see how good your score is by how well it correlates with what you wish to predict. It does not matter, for the most part, that you are not an engineer at Intel who can design a modern RISC CPU from ground up. If you were to test a car, it sure helps to know a little about cars, but you do not need to be able to build an engine to perform meaningful tests on cars.

You still express a whole bunch of complexity in a single number. I see a lot of references to statistics in this thread, so I am surprised there is so much pushback against a concept that is practically just a factor analysis. It does not matter that you get a single number or a few factors in the end. What matters is how well that set of factors correlates to the metric you are interested in, how much of the variation the set of factors predict. What we are interested in, cognitive performance on g-loaded tasks, is very well correlated, based on available studies. This has been alluded to already and it is what is often referred to as the observation that performance on particular tasks is on a so-called “positive manifold", and, according to Spearman's hypothesis, can be expressed as the g-factor, i.e. if you are better than someone else on one g-loaded task you are likely to also be better on all g-loaded tasks.

Spearman, Charles. “‘ General Intelligence,’ Objectively Determined and Measured.” The American Journal of Psychology 15, no. 2 (1904): 201–292.

What the g-factor might represent is something like a metric how well your brain works. That would be consistent with IQ even strongly correlating with factors that seem to have nothing to do with intelligence at all, such as the already mentioned reaction speed, but also color acuity. The higher your IQ, the higher your color acuity typically is (r=-0.68, between total error score and verbal IQ):

Cranwell, Matthew B., Bradley Pearce, Camilla Loveridge, and Anya C. Hurlbert. “Performance on the Farnsworth-Munsell 100-Hue Test Is Significantly Related to Nonverbal IQ.” Investigative Ophthalmology & Visual Science 56, no. 5 (2015): 3171–3178.

Woodley of Menie, Michael A., and Heitor B. F. Fernandes. “Showing Their True Colours: Possible Secular Declines and a Jensen Effect on Colour Acuity — More Evidence for the Weaker Variant of Spearman’s Other Hypothesis.” Personality and Individual Differences 88 (January 1, 2016): 280–84. https://doi.org/10.1016/j.paid.2015.09.009.


Take an example test here: https://www.colormunki.com/game/huetest_kiosk

(It’s probably not perfect because a bad screen can give you an unfair disadvantage. Obviously, if there is something wrong with your vision, this would not be a good metric, either.)

But here is where the confusion sets in: this applies to g-loaded tasks. There are many tasks that might require huge amounts of memorization (some memorization abilities do correlate with IQ) or some that are not g-loaded, but which we commonly associate with "being smart", where aspects of endurance, motivation, and character are more decisive than your IQ. But that is not a shortcoming of IQ, that is a misunderstanding of what constitutes intelligence, or what we mean by the word in different contexts. Chess, for example, is apparently less g-loaded than often portrayed in popular culture, so, even though it's an advantage to be more intelligent in chess, other factors, possibly related to personality, might outweigh pure IQ differences.

There is also misunderstanding how much IQ must have some direct biological correlate in order to be useful or valid, which is sort of expressed when asking how we can measure when so much of the brain’s structure remains unexplored. In order for a construct to be valid (referred to as “construct validity”), however, it does not mean that IQ cannot simply be a purely psychometric artifact. In principal component analysis, for example, a mix of features that correspond to the original aspects being measured can be subsumed in a single eigenvector and that eigenvector has a corresponding eigenvalue, which roughly speaking corresponds to the contribution the component makes to the overall variance of the underlying data. But the principal component itself might be largely meaningless (from the perspective of being interpretable as a directly observable aspect of the object measured) and have no intuitive unit associated if taken as a metric, like mile, pressure, or weight. But depending on how much variance of the data it predicts, it can tell you how good of a measure it would be if it stood in for the original data. The eigenvalue can be a completely arbitrary number (technically it need not even be normalized I think), yet, it is dismissive to just say that it is an oversimplification of a complex system because we chose to express a highly predictive and representative aspect as a single number.

Examples to play with yourself:

https://wilkelab.org/classes/SDS348/2016_spring/worksheets/class9.html
https://stats.idre.ucla.edu/r/dae/canonical-correlation-analysis/


I am only using PCA as an example, not making a statement about how appropriate it would or would not be for FSIQ in WAIS, WISC, etc. Similar illustrations could probably be made with canonical correlation analysis (CCA) and other methods of factor analysis or construct validation. But it also illustrates that there is room for other factors, where Big Five Personality (NEO, MMPI, etc.) might come in. You can test that by looking at how much variance is explained by your model, how much these additional factors add to the predictive accuracy of your model.

Last but not least, why should we expect there to be a single factor of general intelligence in the first place? That is actually a question that people who defend the use of IQ do not explain well. In fact, there is no good reason to simply assume that and studies on animal intelligence have actually shown that some species might show a much stronger clustering of abilities. Spearman’s hypothesis might not apply universally. Chimpanzees, for example, might have such a clustering. Mice, on the other hand, appear to have general factor of intelligence similar to humans and it seems to explain a similar size of variance in cognitive performance.

I did not go into the basics of distributions. There are many people, even policy makers, who either pretend to or do not understand that a statement about a group or statistic does not allow one to make direct determinations about individuals. But here is a calculation example:

Assume that a population has a mean IQ of 85 with a standard deviation of 15. That would mean that (1-pnorm(120,85,15))*100 ≈ 0.98% of such a population would have an IQ above 120 (use the cumulative distribution function of the Gaussian distribution and subtract it from 1.0 to obtain the portion above the upper limit of the integral). If you had a population of a million, there would still be about ten thousand such individuals. Some R code for that here: https://ideone.com/EtxYKl.

Another frequent question is to ask why any of that is useful for dealing with individuals. It is not. But we do not exclusively deal with individuals. That is like asking why statistics or sociology are of relevance. When you deal with groups of people, you use a level of analysis that is appropriate for groups. When you deal with an individual, you use a level of analysis that is appropriate for individuals. For example, if you were to design a seat for a car, complete with seatbelt, it would be useful to know how potential drivers are distributed according to weight and height. You would be interested in such statistics as mean weight/height, standard deviation/variance, and p-values of a given confidence interval to be reasonably sure your car is safe. When you have someone come in for an interview, it would be silly to pull out population statistics of the town they were born in. You would use metrics that are more applicable to an individual, such as academic achievement, university attended, years of experience and so forth. But that does not mean statistics are unimportant. Far too often are they misused and any difference in (statistical) outcome is used as evidence for discrimination. For that reason alone it would be good for us to accept population differences in IQ, if there are such differences, and stop chalking up every disparity to evil racists.

And because it is a distribution there are naturally also outliers like Kim Peek, who was able to perform incredible feats of memorization but does not measure very high on IQ tests, consistent with his general difficulty to navigate common life situations autonomously: https://www.youtube.com/watch?v=36K1HQvUdWg

But outliers are not evidence that statistics is wrong, nor is it evidence that it's not useful. It can also certainly be unfair to an invidividual. Work some time at an insurance company. Some teenagers might be perfectly safe drivers, but if you have a large population of people, it is in your financial interest as an insurance company to do a good job on estimating the probability that a given driver, absent of a long driving record, is going to get into a car accident you might have to pay out for.


Matzel, Louis D., and Stefan Kolata. "Selective attention, working memory, and animal intelligence." Neuroscience & Biobehavioral Reviews 34, no. 1 (2010): 23-30.

Deary, Ian J., Steve Strand, Pauline Smith, and C. P. D. Fernandes. “Intelligence and Educational Achievement,” 2007. https://doi.org/10.1016/j.intell.2006.02.001.

Reynolds, Matthew R. “Interpreting the g Loadings of Intelligence Test Composite Scores in Light of Spearman’s Law of Diminishing Returns.” School Psychology Quarterly 28, no. 1 (2013): 63–76. https://doi.org/10.1037/spq0000013.

Rushton, J. Philippe. “The ‘Jensen Effect’ and the ‘Spearman-Jensen Hypothesis’ of Black-White IQ Differences.” Intelligence 26, no. 3 (1998 ): 217–225.
Answer your other 4 questions, xi jinpeng.
 
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