Boris: not good enough
The Mayor of London, Boris Johnson, on equality:
‘It is surely relevant to a conversation about equality that as many as 16 per cent of our species have an IQ below 85,’ before facetiously asking the audience if anyone had a low IQ.
Now, there are lots of problems with the over-intepretation of IQ as a predictor of economic success. There are problems with the definition of IQ from factor analysis: positive correlations between test results will lead to an apparent single factor explaining them, even when this about as untrue as possible.
But that’s not the most egregious statistical point. IQ, because it’s a hypothetical reconstruction, not a directly measured thing, doesn’t have any intrinsic values. When you design tests to estimate intelligence, you can choose to scale the mean and spread of the distribution to be whatever you like. The people who designed IQ chose to set the mean at 100 and the standard deviation at 15. That doesn’t tell you anything about how variable intelligence is between people, it’s just a choice of scaling, part of the definition of IQ.
Boris’s observation that 16% of people have an IQ below 85, then, is absolutely content-free. It’s like saying our schools are bad because 50% are below the median, or that NZ rugby teams aren’t very good because only one of them holds the Ranfurly Shield. The fact that more than 1 in 7 people is below the 16th percentile is, actually, not at all relevant to a conversation about equality.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »
I think perhaps the reporter missed the placement of “facetiously”; it should have been the opening for the entire quote.
10 years ago
Funnily enough I tend to think you are making Boris’ point. Only one team can have the Ranfurly Shield, because (at any one time) one team is better/luckier that the rest. That is just the way things are. Similary with the attributes that lend to economic success, some have more – and “yes” IQ helps. A small wager – not to many people with an IQ below 115 are doing post grad studies in semiparametric models?
10 years ago
Not at all. The fact that only one team can have the Ranfurly Shield at a time tells you absolutely nothing about how much better they are. If all teams are are about equal, one will win and the others won’t; if there’s enormous variation between teams, one will win and the others won’t.
Similarly, the fact that 15% of the population are below 85 IQ tells you nothing about equality, only about the definition of IQ. If there were almost no variation between people, 15% would be below 85; if there were a huge variation, 15% would be below 85. This fact tells us nothing about equality.
Now, if he’d said that ordinary experience with the public makes you think some people can’t cope with life, that would be an assertion with some content, and would be relevant to a discussion of equality. It might not imply Boris’s conclusion — many people would take it as evidence that more needs to be done to promote equality, rather than less — but it would at least be relevant. But in trying to make this sound objective and scientific, he has made the statement completely vacuous.
PS: I don’t actually know the IQ of anyone who has done or is doing post grad studies in semiparametric models, so I wouldn’t want to speculate. Perhaps you do.
10 years ago
Dont you think you are reading too much into what he said. His main point was that he believes that economic inequality is inevitable, and (unlike some others) he approves. To the extent that he is quoted as mentioning IQ, I suspect its to make the point that economic inequality follows from inequality in other attributes that people have (Like IQ). I dont disagree either, though I would add that luck also plays a big part in economic inequality. I doubt if he was trying to be scientific – he never has before. If he was repeating a characteristic about IQs, certainly many others believe the same thing, because -as you also say – that’s how they are designed.
10 years ago
It seems to me that people who want to justify inequality are very often caught using botched metrics that have little to do with the real world (IQ being the best exemplar of these).
10 years ago
“Only one team can have the Ranfurly Shield, because (at any one time) one team is better/luckier that the rest.”
This is not correct. Only one team can have the Ranfurly Shield (at any one time) because the decision was made to give it to just the one team (at any one time).
Imagine a property, x, which varies but has five people with the greatest level of x.
Now give an award for reaching this level: there are obviously five awardees.
A decision to award just one produces just one awardee.
– Decsion made results in one
– Decision not made does not
The single awardee is down to the decision and nothing at all to do with the underlying distribution of x.
10 years ago
So true Tony the decision was made to award it to one team at a time, which is why its correct to say ““Only one team can have the Ranfurly Shield” And that is how it parallels the IQ issue – a decision was made to make sure that x% would score below 85 and that an IQ of 100 would be the average. In the case of the RS the designers thought about the possibility that two teams would get the same score – in which case the holder gets to keep it.
10 years ago
Another interesting link on the same issue, with a bit more of the BJ speech quoted
http://languagelog.ldc.upenn.edu/nll/?p=8711
10 years ago