05 May 2012

Has the bell curve shifted?

One expects any variation in the IQ bell curve to show up most noticeably at the upper and lower ends, where the percentages approach zero along the x-axis.

It used to be said that the female bell curve was narrower than the male; so women were much less likely to be geniuses, but also much less likely to be idiots.

The shift in the bell curve subsequent to the onset of the Welfare State may well have caused a significant reduction in the numbers of people with IQs above 150 or 160, as the mean has shifted downwards. But if it has done, it has also created an even greater increase in the population of the dysfunctional, with IQs below 50 or 40. I speculated that if the number of people above a certain IQ level (100 + x) has been reduced to 1/n of what it was before the shift, then the number of people below (100 – x) might well have been multiplied by something like n.

My speculation turns out to be not too far off. If you reduce the population of the exceptionally intelligent by shifting the bell curve, without changing the shape, you more than correspondingly increase the population of the most dysfunctional.

Say that, before any shift takes place, the proportion of the population with an IQ over 140 is 0.38%. A shift in the mean of one point downwards reduces it to 0.31%, and a shift of 2 points to 0.25%. A shift of 5 points reduces it to 0.13%, which is about one-third of 0.38%. So in this case the number of people in the population with IQs over 140 has been reduced to a third of what it was.

The shift of the mean to the left would also have affected the proportion of those with IQs below 60, originally also 0.38%. A shift in the mean of 5 points downwards makes it 0.99%, i.e. 2.6 times 0.38%. Reducing the proportion of the population with IQs above 140 to a third of what it was, has at the same time increased the number of those with IQs below 60 (which is fairly dysfunctional for any purpose) to nearly 1 percent of the population, making a group formerly thought of as marginal into a considerable element in the total population.

If there are now one-third as many people with IQs above 140 as there were before the shift, say, then there are now about three times as many with IQs below 60. The reduction in the population of really high IQs may have something to do with why we (the real University of Oxford in exile) find it so difficult to increase the number of our associates, but it is otherwise easy to overlook.

What is probably less easy to overlook, if one is in a position to observe it, is the multiplication of people with low IQs and other genetic deficiencies who can never be self-supporting.

This is clearly a tremendous drain on taxpayers’ money, although it is diffused throughout the general cost of benefits, the NHS, ‘education’ and ‘social services’.

What is paid out to pensioners, on the other hand, is clearly identifiable. Pensioners are a section of the population with an average IQ above the mean for the population as a whole, so the finger can be pointed at them, and the process continued of transferring resources from the above-average to the below-average.

A graph illustrating the possible shift in the bell curve, with close-ups of the tails:

Graphics by Andrew Legge

The relevant departments of my unfunded independent university are effectively censored and suppressed. They have been prevented for decades from publishing analyses of the complex issues involved, while misleading and tendentious representations of them have continued to flood out from socially recognised sources.