Linguist: I can use R, you can’t. Thus, your motives are questionable. QED.

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Mark Liberman at Language Log (a blog which I very much enjoy, I should point out) approvingly links to Cosma Shalizi’s rant against Slate for publishing a series of articles on race and IQ. His conclusion:

So to start with, you should ask yourself whether you can define and calculate the variance of a set of numbers, or the correlation between two sequenccs of numbers. If not, then read the (linked) wikipedia articles — and spend a little time playing with the concepts in the context of an interactive program like R. Once you’ve paid that entry fee, read Cosma’s posts. (It’s more fun that you might think — I especially recommend the discussion of the heritability of zip codes, and you could go back and read the prequel about the heritability of accent.) And then go through William Saletan’s articles, and decide for yourself what they mean about the abilities and motivations of the writer and his editors.

It’s amazing how quickly people go from simple disagreement to armchair psychologist mode; a little perspective is in order here.

Dr. Liberman assumes that Cosma concludes that heritability estimates are worthless. This is not the case. Cosma points out that estimating heritability involves making assumptions that are often incorrect, but (I feel like I’ve said this many times before) all models are wrong, but some are useful. And buried in his prose (which contains many important, ill-understood points about the estimation of heritability), he cites a nice paper on the heritability of IQ, which concludes for a narrow-sense heritability of ~0.34 (that is, additive genetic factors account for ~34% of the variance in IQ, see the linked post). Cosma wants to add additional parameters to this model before he makes any definitive statements, but he can’t bring himself to treat IQ differently than other traits:

If you put a gun to my head and asked me to guess [whether there are genetic variants that contribute to IQ], and I couldn’t tell what answer you wanted to hear, I’d say that my suspicion is that there are, mostly on the strength of analogy to other areas of biology where we know much more. I would then – cautiously, because you have a gun to my head – suggest that you read, say, Dobzhansky on the distinction between “human equality” and “genetic identity”, and ask why it is so important to you that IQ be heritable and unchangeable.

So if he had to guess, there is probably a genetic component to IQ, environment also plays a role, and human equality is not dependent on genetic identity. Seriously, read Saletan’s columnthese are exactly his points!

Referring back to my point about the utility of incorrect models, it’s worth noting that, if you don’t accept any of the heritability estimates proposed in humans, you’re rejecting that any trait could be determined to have a genetic component before, oh, 2001. I don’t think that’s a good idea, and here’s why: the heritability of type II diabetes was estimated at a “mere” 0.25 (using all those horribly flawed methods, and including, since it is a dichotomous trait, even more assumptions); now molecular studies have identified at least 9 loci involved in the disease. The heritability of Type I diabetes was estimated at about 0.88; now, there are 10 loci undoubtably associated with the disease. There are other examples, and more sure to come, but suffice it to say that heritability studies, with all their seemingly ridiculous assumptions, are not worthless.

Now look to Cosma’s post on g. Again, this time in the footnotes, we see something in line with Saletan’s article. Referring to the observation by economist Tyler Cowen that some people he knew in a village in Mexico were smart in ways not measureable by IQ tests, he writes:

Cowen points out behaviors which call for intelligence, in the ordinary meaning of the word, and that these intelligent people would score badly on IQ tests. A reasonable counter-argument would be something like: “It’s true that ‘intelligence’, in the ordinary sense, is a very broad and imprecise concept, and it’s not surprising the tests don’t capture it perfectly. But the aspects of ‘intelligence’ they do capture are ones which are vastly more important for economic development than the ones displayed by Cowen’s friends in San Agustin Oapan, however amiable or even admirable those traits might be in their own right.” This would be a position about which one could have a rational argument. (Indeed, I might even agree with that statement, as far as it goes, as might A. R. Luria.)

So Cosma “might” agree that intelligence, as operationally defined by psychologists, is important for economic development and differs in distribution between groups. Interesting.

Cosma’s posts seem to follow any discussion of IQ around in the “blogosphere”. They’re well-written, include legitimate discussion of many important issues in quantitative genetics and IQ testing (ok, I don’t know much about IQ testing, but I’m assured this is the case by people who do), and come from an authority. But for whatever reason (I’m tempted to think that people don’t actually read what he writes. I mean, it has, like, math and stuff), he’s interpreted as saying that intelligence tests and the concept of heritability are entirely meaningless. That is not the case.

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22 Comments

  1. Over at Matthew Yglesias’ blog posting about the Baruku and intelligence improvements once they get to the greatest Western Country proving that all claims of an association between IQ and achievement are conservative racist justifications for white males being on top we see a comment that: 
     
    Also, as Ezra Klein has noted, when IQ tests are translated into ebonics (which some linguistics, such as McWhorter, point as has all the grammatical and syntax structures of an actual language) without changing the question and answers, the black-white gap disappears. 
     
    An interesting claim. I wonder if there is any data to back it up?

  2. The main reason would be that Cosma’s rhetoric invites this misinterpretation.

  3. Also, it is a bit funny to believe that saying “IQ has a heritability of .6″ makes one a horrible racist, but saying “IQ has a heritability of .5″ means your an ok guy.

  4. Also, as Ezra Klein has noted, when IQ tests are translated into ebonics (which some linguistics, such as McWhorter, point as has all the grammatical and syntax structures of an actual language) without changing the question and answers, the black-white gap disappears. 
     
    iirc, exactly the opposite is true. 
     
    from Neisser et al (1996):  
     
    Characteristics of tests. It has been suggested that various aspects of the way tests are formulated and administered may put African Americans at a disadvantage. The language of testing is a standard form of English with which some Blacks may not be familiar; specific vocabulary items are often unfamiliar to Black children; the tests are often given by White examiners rather than by more familiar Black teachers; African Americans may not be motivated to work hard on tests that so clearly reflect White values; the time demands of some tests may be alien to Black culture. (Similar suggestions have been made in connection with the test performance of Hispanic Americans, e.g., Rodriguez, 1992.) Many of these suggestions are plausible, and such mechanisms may play a role in particular cases. Controlled studies have shown, however, that none of them contributes substantially to the Black/White differential under discussion here (Jensen, 1980; Reynolds & Brown, 1984; for a different view see Helms, 1992). Moreover, efforts to devise reliable and valid tests that would minimize disadvantages of this kind have been unsuccessful. 
     
    Moreover, language effects cannot explain the BW gap on nonverbal IQ tests. The BW gap does vary from test to test, but supperficial features of test content do not explain the differences. Instead, the magnitude of the BW gap is correlated with the degree to which each test measures g. There may be more to the BW gap than g, but the gap is a function of the constructs that cause individual differences, and not a function of test construction.

  5. So why doesn’t suggesting that black people are lazy, unable to cope with standard English, and intimidated by white people make you a horrible racist? 
     
    It seems to me that all of the proposed explanations for the test differences are WORSE than simply postulating an IQ gap.

  6. Also, while we’re on the subject, interested readers should note that recent reports of genetic associations with IQ should be taken with a grain of salt. The standard that one should apply to association data, regardless of the phenotype, is (a) statistical significance to a genome-wide level and (b) replication in an independent population.

  7. interested readers should note that recent reports of genetic associations with IQ should be taken with a grain of salt 
     
    absolutely. for people interested in genetic association studies (ie. studies which attribute parts of the heritability of a trait to individual loci), check out these two reviews: 
     
    http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=15716906&cmd=showdetailview&indexed=google 
     
    http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=15716907&cmd=showdetailview&indexed=google

  8. does anyone think that cosma’s posts are that value-added without knowledge of linear algebra? and does anyone think that most people who link to it do really know linear algebra? my basic prediction that his post is going to be cited for years to come seems to already have been validated. in any case, it is worth reading, as is a close reading of the literature from the hereditarian side. the most annoying thing is that people on both sides link to their supporting arguments without much deep understanding of what they are saying on a technical level.

  9. My complaint about Cosma’s little thought-experiment is that it so cleverly avoids the single fact that does the most to convince me that g is not an artifact. 
     
    This is that it’s basically impossible to construct a new test which (a) looks anything like a test of generalized cognitive dexterity, and (b) is not broadly correlated with g. And we know this because a lot of people have tried. 
     
    I am not a statistician, but my impression of Cosma’s argument is that he’s found a very elaborate way to claim that data mining could account for the pattern of correlation seen in g
     
    Data mining (or snooping) can indeed create illusory patterns. But when the algorithm you found by mining the sample data turns out to also work for out-of-sample data, the case for illusion gets a lot harder to make.

  10. Shalizi talks a good game in his g simulation, but by assuming the existence of shared abilities, he’s already conceded that a general factor exists. We could take the average of the shared abilities and label it “IQ” – it would predict all outcomes. Now, this does not prove whether this general factor is a _single_ ability, or the combined effect of many – but as Mencius says, in this case the absence of evidence becomes evidence of absence (of abilities uncorrelated with g).

  11. A big point of Cosma’s post was that the existence of a large first factor is not the proof of the existence of a specific ability called g. Its a theorem. The first factor is an average of many abilities (14 in the WAIS), so that anything that taps into a different average of those abilities is going to be correlated with g. If you want something orthogonal to g, then you will need to start taking averages of differences of those abilities.  
     
    Part of this gets into the whole idea of psychological measurement. You might want to look at the measurement theory faq for some pointers into this sub-area

  12. @ Caledonian 
     
    The most important reason that people are upset about genetic dependence of IQ seems to me to be because it makes your life too deterministic. People want to have the illusion/hope that they can improve their lives.  
    So if you tell them that their situation is bad because they are lazy,etc then you are suggesting that if they change those behaviour then things can improve.  
    However if you say it is genetic, then it is like their height (which is limited though not always by the parents’ heights). 
    So the argument becomes less of a scientific fact and more of a political one.

  13. Cosmo reminds me though to look at the evidence of the race/IQ connection more carefully.  
     
    If there existed a pill that some one claimed ( could give you (or your child) the IQ of an (average) North east asian would you use it based on the evidence presented so far? Small Observational studies with non-random samples, no solid biological mechanism, no animal studies?

  14. If there existed a pill that some one claimed ( could give you (or your child) the IQ of an (average) North east asian would you use it based on the evidence presented so far? Small Observational studies with non-random samples, no solid biological mechanism, no animal studies? 
     
    That’s the wrong question. The right question is, based on the evidence we have, would you choose to have the average IQ of  
     
    a) Ashkenazi Jew 
    b) East Asian  
    c) Western European/American Caucasian 
    d) African 
    e)……..

  15. e) Australian. 
     
    http://www.news.com.au/story/0,23599,22836100-2,00.html 
     
    No wonder so many of my countrymen drive huge SUVs everywhere – they can’t decipher the bus timetables.

  16. I’ve seen Cozma’s post (on “g” being a myth) linked to frequently on sites like Crooked Timber as a sort of holy relic to ward off the “g” vampires. They link to it, then say that if you can’t comment on it, then you’re not qualified to assert that g is heritable. It’s an attempt to intimidate, because the post is long and full of math. 
     
    Trying to be conscientious, I took the time to go through it. The math is correct, but the premises are incorrect. Cozma’s model starts by assuming a bunch of factors which are all positively correlated, then makes a big show of showing how randomly-generated numbers still lead to a g factor. This is slight of hand, because the numbers are *not* random between -1 and 1, but rather between 0 and 1. The reason that g is meaningful is that the real-world correlations are all positive, which is by no means what you’d expect from random chance. 
     
    Additionally, there was a roundup of gene-iq links posted recently which mentioned that many of them operate via the same basic mechanism. What do you get if you flip a coin many times? a normal distibution. what do you get when you flip many genes, which all operate similarly? a normal distribution. What does the distribution of IQ look like? it’s normal. 
     
    Cozma’s post is being linked to by people who want it to be a defense against hereditarianism, but it’s actually, when you boil it down, and elegant argument IN FAVOR of heriditarianism. 
     
    That’s why those impassioned postings on Crooked Timber and the like crack me up so much now.

  17. I read your paper on race that you linked for me. link It was interesting no doubt, but I found it made a rather poor case for the use of race as a meaningful scientific term. 
     
    If you cluster for genes known to be responsible for eye color, skin color, hair color and the like, you’ll be able to approximate the actual geographic spread among the 5 continents… fine, although as you noted “Some populations were exceptions, of course (there are always exceptions in biology)– they seemed to be a mix between two clusters, or could even form their own cluster in certain models.” 
     
    You go on to use an example that only includes Nigerian, West European, Chinese, and Japanese. Then the case you made was rather curve-fit, but even if we accept your premise… what’s the point here? You could even narrow the categories further to get better answers. Why not 1,000 races?  
     
    The Ainu are genetically different from the majority of Japanese. Masai are quite different from there neighbors as well. You even admit that in Brazil “skin color and genetic ancestry are becoming independent.” Certainly that would also be true to a lesser degree in other mixed populations across the Americas? People seem to be willing to admit admixtures of 20-25% European blood in US blacks, but they don’t ever want to address the amount of African blood in US whites… remember, the law was 1/16 or less and you were white. Of course, there was the ol’ black sheep in the closet trick to speed that up as well. 
     
    Let’s not forget that interbreeding is growing year by year. Should all the interracial people of the world be forced to choose a side?  
     
    So again. What good is this? We have finer tools in our shed. In fact, you are using finer tools to prove the validity of a clumsy and blunt one. 
     
    Your own final point on race as a social construct hammers this home.  
    “To some extent, of course it is–some people that would be called “black” in the US might not be called “black” in France…” 
     
    Can we move on already? Let’s treat people as individuals, and get on with the show. You don’t have to go back more than a few thousand years to find an MCRA for us all… Isn’t this all a waste of time? Unless, of course, you have some vested interest in this race notion…

  18. I found it made a rather poor case for the use of race as a meaningful scientific term. 
     
    fair enough. call it population structure then. the point is that “race” correlates with genetics, however imperfectly. 
     
    You could even narrow the categories further to get better answers 
     
    absolutely.  
     
    I closed comments on the last thread because I found it getting tiresome (in public forums, people seem to do a lot of grandstanding). feel free to email me if you have further comments.

  19. Can we move on already? Let’s treat people as individuals, and get on with the show. 
    You’re so right. No more referring to these fuzzy sets like “male” and “female”, because there are exceptions, and you can’t tell by looking. If someone asks, “Where is the restroom?”, you would have us unfailingly inquire, “Which one?”  
     
    slap! 
     
    A world without groups is not only practically impossible, it’s a complete waste of time. What’s needed are informative group designations that are predictive — albeit imperfectly! — of important underlying traits. Race, for right now, is such a designation. (That said, I do advocate rampant interbreeding as a solution to the whole mess.)

  20. That said, I do advocate rampant interbreeding as a solution to the whole mess 
     
    you practice what you preach? ;-)

  21. indeed i do. but as a less-able whitey, you’ll forgive me for being an asian charity case. :)

  22. see, even my sentence construction reflects my crappy genes! i’m sure you smart ones will figure out what i meant.

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