Wednesday, January 17, 2007

You Do the Math

My sweet old grandma (as opposed to my bipolar Vicidan-popping grandma) once said, "I think most people are better than average looking!" Hearing this, even at the age of six, I knew her math was off. But that's because I'm of siginificantly above average intelligence.

I hear a lot of folks complaining that only half of people have an IQ above 100, implying that our species is facing an epidemic that warrants correction. Unfortunately, we can't pull more people above the 100 mark if, by definition, 100 marks the median IQ, and if, by definition, the median marks the 50th percentile rank. Try as we may, half of all people will always below the median of intelligence (and looks, and dancing ability, and fitness, and income, and "Futurama" fast-action recall quoting ability).

Of course when people suggest life would be better if more people had IQs above 100, they don't literally expect the basic principles of statistics to bend to their will. Instead, they're imagining a utopia of an absolute, rather than relative, IQ jump within the population. These critics are treating IQ like fixed-value dollars, like when you see charts comparing skilled labor wages from 1890 to 1990, and in the bottom there's a little note that says "All figures in 1990 dollars." Ideally, the average IQ would go up in fixed "2007 IQ dollars."

But, not surprisingly, the world average IQ
is continually going up in fixed 2007 IQ dollars! It's called the Flynn Effect, and its causes are highly logical. It's like inflation for the population's brain. You can tell your kids, "Back when I took the IQ test, a 148 actually meant something. You could take the SAT, solve one of those Sudoku puzzles, buy a pop, and still have 38 IQ points left over to put toward your M.A."

I don't get too worked up when folks talk about IQ in casual terms, either complaining about how stupid everyone is or about how stupid everyone isn't. I do get worked up, however, when the quest for higher fixed-value scores on intelligence measurements negatively affects policy or prompt society to dismiss the value of entire groups of citizens. The IQ test is a severely flawed measurement of individuals' intelligence--it's riddled with cultural biases that favor wealthy white males--and neither the IQ test nor any other single measurement tool should sway policy.

This op-ed in the Wall Street Journal disappointed me in its conclusions. The author, unlike many, displays a proper understanding of the math behind IQ distribution (what a relief!), but he persists in treating IQs as a re
liable measurement of individuals' base educational potential:
Our ability to improve the academic accomplishment of students in the lower half of the distribution of intelligence is severely limited. It is a matter of ceilings. Suppose a girl in the 99th percentile of intelligence, corresponding to an IQ of 135, is getting a C in English. She is underachieving, and someone who sets out to raise her performance might be able to get a spectacular result. Now suppose the boy sitting behind her is getting a D, but his IQ is a bit below 100, at the 49th percentile.

We can hope to raise his grade. But teaching him more vocabulary words or drilling him on the parts of speech will not open up new vistas for him. It is not within his power to learn to follow an exposition written beyond a limited level of complexity, any more than it is within my power to follow a proof in the American Journal of Mathematics. In both cases, the problem is not that we have not been taught enough, but that we are not smart enough.
He ultimately falls for the abysmal "you're poor because you're dumb" argument so popular among many conservatives.
It is true that many social and economic problems are disproportionately found among people with little education, but the culprit for their educational deficit is often low intelligence. Refusing to come to grips with that reality has produced policies that have been ineffectual at best and damaging at worst.
If this were true, as fixed-value IQs increased, fixed-value wealth would also increase, which simply isn't happening. We're damned to live in a world where, for any given population, half of all members will sit below the median level of wealth, just as they do for intelligence. And even my sweet old grandma isn't stupid enough to say that being dumb makes you poor.


Jessica said...

Interesting post. I think your grandma hasn't spent much time people watching in large pools.

Tommaso Sciortino said...

Yeah, the "being poor proves that you're dumb" argument is silly. I was thinking though that if you accept that idea, pretty much every other part of the conservative world-view gets assumed along with it.