IQ is the Best Predictor of Human Achievement

For a bit of context, the good Dr. Thompson, on his excellent blog, gives a brief summary of the most important things to know about intelligence (emphasis added):

Intelligence does not guarantee good decision-making in all circumstances, simply better decision-making in more circumstances than a duller person.  Some problems forms are inherently difficult and ambiguous. For example, it is easier to understand natural frequencies than percentages with decimal point. Apart from intelligence, social pressures and emotional attachments influence decisions.
Modern IQ tests give one overall figure, and also figures for 3 to 4 component indices, usually verbal comprehension, perceptual organisation, working memory, plus processing speed. The single figure is usually the best predictor, but the others have their place in specific circumstances. The fact that one single number is the best predictor of human achievements is testimony to its power.
40% is the heritability estimate for children, but it rises to 60% plus for adults.  70/30 is not a bad estimate for wealthy countries, 50/50 for very poor ones…. People from profoundly different cultures make the same sorts of errors on culture reduced tests, and the pattern suggests a largely universal problem-solving capacity. The predictive power of intelligence is similar in culturally different countries.
The point in bold is key. Out of all the factors that people think explain why certain people fail at life and others succeed, intelligence, even as imperfectly but reliably measured by one simple number, is the most important. The way science discovered this is also interesting: by controlling for intelligence in studies of other factors. Level of education, parental socio-economic status, reaction times, etc. turn out to be strongly correlated with, and very likely caused by, intelligence. On average, in the aggregate, the wealthier you are, the smarter you are, and wealthy parents pass those genes onto their children.
This is very different from what many people believe, or wish were true.

5 thoughts on “IQ is the Best Predictor of Human Achievement

  1. The fact that intelligence predicts achievement (because intelligence causes achievement, and also because higher intelligence is found in those whoi are raised in better socio-economic conditions), is not so much disputed, I suppose. Questions remain: which achievement is actually meant? whose achievement is meant (i.e. which populations are we talking about)?
    Moreover, intelligence might be a more powerful predictor than other variables, but as the cited Dr. Thompson makes clear, it is far from being a perfect predictor. As far as I know, the best prediction of intelligence test performance is for academic performance (the demands overlap to a substantial degree, and the time span between intelligence measuremenr and academic achievement is ususally just a few years). It predicts about 30-60% of variance there, which is excellent, but still leaves 40-70% unaccounted for, even under such favorurable circumstances. And, again, correlation is not necessarily causation.


  2. It’s the other way ’round, mutter. And it’s not causation, it’s correlation, albeit very strong correlations. Ceteris paribus, bright parents (1) make more money than dull parents; and (2) pass the genes for high intelligence on to their children. Which in turn makes it likely those children will have above-average incomes.


  3. @mutter
    > I doubt that my my parents’ socio-economic status is very likely
    > caused by my intelligence. Just sayin.

    Your parents’ socio-economic status is very likely caused by their intelligence (At least when trying to rephrase your sentence so it makes, uhm, even more sense. To be precise: the variance in socio-economic status among the social, ethnic, and, God forbid, racial group your parents belong to when data is controlled for possibly confounding factors is most parsimoniously explained by the assumption that it depends mostly on their intelligence, whose variance in turn is mostly heritable). That may or may not be true for all I know because I’m not a scientist, nor am I as perceptive as you are. For which your deserve to be lauded. But that is what follows from how Andrew summarizes Dr Thompson’s take. Which is what bad scientists have been knowing to be an old chestnut* for the last half century or so, while good–ie social–scientist knew and know it to be false, or at best grossly distorting, or else without real world application and relevance.** Because else they don’t get to squeme grand squemes. And they don’t get them funded. Anyway, it’s good you just were sayin’ something, for that is exactly 100% better than having said nothing, so there’s reason to thank you on behalf of all readers past, present, and future.***

    * Trivial in scientific parlance–trivial at least to all who don’t get allergic skin conditions or nervous breakdowns when applying math to empirical data. Which happens to be out there in abundance, starting with Western armies testing millions of recruits since about a century in order to sort out efficiently those among them with eg the tendency to constantly and reproducibly shoot in their foot and not at least in the general direction of the front thus ensuring that at least occasionally it’s the foot of the other guy.

    Stats are murder. Maybe you want that for a bumper sticker or a gravestone.

    ** or they wisecrack ‘ correlation is not necessarily causation‘ (thx, Ney; adding necessarily is a subtle twist)

    *** did you know your nick spells “nutter” when adding minimal variance to the premises?


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