There\’s a problem with this sort of statistic

One set of data shows children’s average vocabulary scores at the age of five – when pupils start compulsory education – and ranks them from one to 100.

Children with highly educated parents in Britain – those who had at least a degree – ranked 67 on average, while those whose mothers and fathers left school with few qualifications had an average rank of 29.

The 38 point gap was “significantly larger” in Britain than in all countries other than America, where it extended to 46 points.

The problem being that there\’s more than one possible way of explaining it. A bit like that conundrum about the way prices move in a perfectly competitive and in oligopolistic markets. They\’ll move in concert in both cases and purely observing the price changes doesn\’t tell you which type of market you\’re observing.

Here the way we\’re encouraged to interpret the numbers is that highly educated parents educate their kids, teach them to read, talk to them with their larger vocabulareies, before the children go to school. And that the schooling for poor children in the UK is shit.

In a blow to Labour’s education legacy, the watchdog said schools serving the poorest 20 per cent of pupils were four times more likely to be “inadequate” than those for the wealthiest 20 per cent.

I certainly wouldn\’t disagree with either point.

However, it is possible to look at the same statistics and come to a very different conclusion. Assume that intelligence is inheritable (which it is, it\’s the extent to which it is which is scientifically disputed…..ignore the numpties further left who insist that each and every child is an equal blank slate upon which society draws).

We could then say, well, so what? The Anglo Saxon societies have got it right: the intelligent are getting the uni educations, excellent, the dim are not. And that carries on into the next generation as intelligence is inheritable. We would expect the children of the intelligent to be intelligent, the dim dim and that\’s all we\’re seeing.

No, I don\’t believe it either, not as starkly as that, but it is a possible conclusion to draw from those bald statistics.


11 thoughts on “There\’s a problem with this sort of statistic”

  1. So Much For Subtlety

    Assuming genetics play a part, I think we should all do our bit to reduce the gap.

    For my own part, I pledge to work even harder to have even more children with Weather Girls and assorted bimbos.

    I suggest to the expensively educated women among us that they continue to bang the ground staff.

    It is all for the best in the long run.

  2. A vocabulary test? So they’ve done statistical controls for mother tongue and anything else potentially relevant – race, religion, age of parents, number of parents in family, presence of grandparents, etc, etc? Or have they just controlled for maximum headline seeking?

  3. Can we blame Polly and the Wimmins’ Libbers?

    Lots of girls (presumably, on average, the more intelligent ones) go to university and into the professions. So above-averagely intelligent men meet above-averagely intelligent women and (eventually) have babies together.

    Thick prole men meet thick prole women and have thick prole babies (I’m summarising here).

    So the genetic component of intelligence becomes more concentrated.

    But back in the good old days, when only men went to university and decent jobs, the female intelligence was spread around a lot more, and so genetically inherited intelligence was more widely dispersed.

    Tim adds: That’s certainly a good account of rising household inequality, two professional families as against no worker families.

    I think you’d struggle to do that with intelligence though. Q tends to revert to mean so it’s not as inheritable as some like to think.

  4. But if both parents are in work and the kids are packed off to childcare, how much conversation do they actually get? Seems like they’d get more chit-chat from the stay-at-home single mum. So the evidence points further towards nature, not nurture.
    (Although the data didn’t mention whether one or both parents was in work, so that may be irrelevant.)

  5. I’d put money on their being an inverse correlation with immigration with a large part of it being causation as well.

    Not that I see immigration as a bad thing, but even the children of the highly qualified immigrant are likely to have trouble with the native language in this sort of test.

  6. I wonder if one of the reasons for this gap being greater in English-speaking nations might be that the vocabulary of the language is so much greater than that of any other language. Perhaps the best English-educated children simply know many more words, in absolute numbers, than those with other native languages? And therefore, the relative difference is that much greater?

    BTW I tried to access this post via a Vodafone mobile account and was told in no uncertain terms that the site is Restricted Access, requiring me to opt in and to be over 18. This of course is normally a requirement for quite a different sort of site – do you think somebody has been up to no good?

  7. Tim, that’s true – I was just extrapolating from your “we would expect the children of the intelligent to be intelligent, the dim dim”.

    And enjoying blaming Polly for rising inequality.

  8. Tim, IQ does not tend to revert to mean. As an economist*, you are an amateur statistician. The original analysis which coined the phrase “reversion to the mean” was a comparison of son’s heights against their father’s height *ignoring the height of the mother*, so it is not surprising that the height of sons of fathers who were 6′ tall with a complete spread of mothers married to 6′ tall men and those of sons of men 5′ 3″ tall with a complete spread of mothers married to 5′ 3″ tall men both reverted towards the mean. It does NOT follow that if they had measured the heights of sons of men 6′ tall married to women 6′ tall they would have got the same result.
    There is no evidence that I have seen that, in the absence of medical problems, the mean IQ of children of intelligent parents reverts towards the mean of 100. A likely explanation of the improvement among poor children in your youth is the improved nutrition during pregnancy compared to their parents. A long time ago, lefties were claiming that IQ was not heritable (unlike blue/brown eyes, black/blonde hair, skin colour, ability to play cricket (Mrs Hutton was rushed up to Yorkshire from watching Len play down south when it was feared she might give birth ahead of schedule so that her son should be eligible to play for Yorkshire – which he did), and I calculated the probability of the only testable set that I knew – my class in the prep school in my village – and I found the likelihood of the chance correlation of its IQ with that of its parents occurring *anywhere on the planet* was less than 5% (maybe 1%, I cannot now remember). IQ *is* inheritable and if there is a regression towards the mean in those not subject to brain damage through illness, birth trauma or brain damage it is of relatively minor importance.
    * by my standards you are an economist.

  9. It would be interesting to see the effect of sports that cause head injury on later brainyness.
    Mostly males of course.
    And whether initiative ( beloved of the military) is more useful than intelligence ( not so beloved)

  10. Steve Hsu’s blog has quite a lot on it about the inheritance of intelligence.

    This article includes the following:

    These estimates are consistent with an additive heritability of at least .7, possibly much higher.

    You could argue the kids are getting a boost from the environmental effect of being raised by eggheads, but adoption data suggests that shared environmental effects are relatively small. I suppose that environmental effects might reduce the additive heritability by .1 or .2 from the range given above.

    More on assortative mating here.

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