Monday, September 17, 2012

Swedish height in the 20th century

Average height of Swedish military conscripts during the 20th century. Looks like an increase of roughly 1 cm per decade or about 1.5 SD in one century. Not unlike the Flynn Effect over the same period.

It was important to generate this curve so that we could properly z score heights of individuals from different birth cohorts. Thanks to my collaborator Laurent Tellier.


Hauser Quaid said...

Is there a saturation for Flynn effect as well?

steve hsu said...

Yes, it appears to have stopped, at least according to data from the UK and a few other countries I have seen.

Ken Condon said...

Topping out at 2 meters is well and good and enough. Any taller and the dents to the skull increase exponentially. And most of the buildings (and furnishings) in the world are just not designed for such freaks.

how to climb said...

interesting blog. thanks for the posts.

Anonymous said...

Sweden has a lot of immigrants. Anybody know if they enlist in significant numbers?

MtMoru said...

Apparently Steve is now in the Flynn effect the result of nutrition camp.

The Wechsler vocab subtest hasn't been affected at all. It is the most reliable and best correlated with g of the Wechsler subtests.

The Ravens has been affected. It is supposedly the best measure of g.

The whole thing is a joke.

Psychology is a pseudoscience.

LaurentMelchiorTellier said...

I believe that the vocab subtest of Wechsler has been significantly affected by Flynn.

Flynn himself recently did a large piece of work on this:

Flynn himself, who seems to agree that vocabulary is probably the most consistent g-psychometric, notes that vocabulary knowledge (as measured by the Wechsler vocabulary
subtest) appears to be progressing faster across generations for adults than children, and that the gap between children and adults it growing - he spends a lot of time speculating on the causes, this might be what you have in mind.

MtMoru said...

Can't read that first. Vocab, arithmetic, and info have been Flynned a little, but to me 4 points is "not at all".

I also remember that over some number of decades American blacks have gained least on vocab of all the subtests.

Richard Seiter said...

It would be interesting to plot height variation and IQ variation on the same curve versus time (were those Swedish conscripts IQ tested?). Seems to me there are several questions here. First, do the Flynn effect and height increase appear to be following similar curves? Second, do the Flynn effect and height increase appear to have the same cause? Lastly, is that cause nutrition? I find nutrition the most plausible explanation for the bulk of both of which I am aware, but that is far from meaning it is proved. @MtMoru what explanation do you favor for the Flynn effect (or the height increase curve above)?

Iamexpert said...

Even more to the point is that brain size has been increasing over the 20th century and brain size has a direct causal effect on IQ. Jensen estimates that roughly half of the Flynn Effect is caused by the rise in brain size. It's unclear what is causing the other half of the Flynn Effect. It could be that nutrition is improving other properties of the brain beyond just overall size, but Jensen believes the rest of the Flynn Effect is caused by greater schooling and other cultural advances which prop up test scores without actually increasing g.

Iamexpert said...

Well some of the biggest Flynn Effects have been found among the Dutch (7 points a decade on the Raven) and the Dutch have displayed MASSIVE height gains.

Iamexpert said...

The vocabulary subtest is no longer the most g loaded subtest on the wechsler scales. It's been overtaken by figure weights and arithmetic. Arithmetic has never showed much if any flynn effect and at times even shows a negative flynn effect, perhaps because kids today are too dependent on calculators. Figure weights is too new a subtest to document flynn effects, but it does show big age differences which implies either a Flynn effect or age declines in this ability.

Vocabulary is kind of useless for studying the flynn effect because language is always changing.

And not all abilities are equally affected by nutrition. Richard Lynn cites identical twins where one twin got better nutrition in the womb and was born with bigger head. At age 15 the big brained twin scored higher primarily on those subtests that show the biggest flynn effects

LaurentMelchiorTellier said...

That's interesting, I did not know that McCrea et al (and others) had recently been able to get arithmetic and figure weights a bit higher than vocabulary on g-loading (0.78, 0.75, 0..74). This does seem to fit; arith items also load a lot on (so-called) verbal intelligence, and are very round. Everything I see still shows a positive Flynn on arith, however; let me know if you have a source for downflynning.

I agree that comparatively slow gains in arith and vocab will be confounded by calculator use and changing language. Nonetheless, they're still top-of-the-line, best-in-field metrics.

Richard Seiter said...

Greater schooling and better nutrition both seem to plausibly align with the observation that the Flynn effect appears to be more a matter of raising scores at the lower end. Does Jensen have much more to say about this (I really need to buy a copy of The g Factor one of these days)? Does the height data also appear to be more raising the lower end of the distribution or are the increases more evenly distributed?

Iamexpert said...

Jensen does believe the Flynn Effect is concentrated in the lower end of the distribution, but my understanding is that it affects the whole distribution pretty uniformly. Height seems to have increased across the entire distribution too, and some research suggests height gains might be greatest among the tallest people.

Iamexpert said...

The positive upward Flynn Effect on Arithmetic appears to be very tiny. Only about 2 points in over half a century:

MtMoru said...

Whatever the explanations the mutabilities of height and IQ show that a short stupid person may just have the misfortune of having been born in the wrong time or place for realizing his potential.

A society in which all may reach their potential is impossible. The culture, norms, and institutions of any one society will be miracle grow for some and agent orange for others, especially when that society is multiethnic/multicultural.

With the exception of geniuses like Srinivasa Ramanujan and the disabled nothing can be learned from the study of "behavioral genetics".

In fact, the behavioral genetics should be dismissed as



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