[yummyfajitas]

Or, perhaps more affluent students are smarter, more conscientious and better prepared for academic work on average, and thus have higher average test scores?

I don't know why everyone assumes that children of the affluent get high SAT scores due solely to test prep. If that were the case, you would expect them to underperform once they reach college, which doesn't occur as far as I know.

Incidentally, at least according to one independent study (as opposed to a study by Kaplan), test prep doesn't help much (30 points on the old 1600 point SAT).

http://online.wsj.com/article/SB124278685697537839.html

[jbooth]

Did you just relate native intelligence to parental income level?

[nostrademons]

Why is this so controversial?

http://infutik.mtk.ut.ee/~jaan_m.ri/work_labour/Strenze_2007...

[jbooth]

The paper you linked has the words "A meta-analytic review of longitudinal research." in its title so I stopped reading. If you want to summarize, I'll take your word for it.

It's controversial because it could be used to justify a number of racial or eugenic policies, and because it's sort of silly, in the melting pot of America, and with our knowledge of intelligence, to make any claims on social classes having stratified into different classes of human within the space of a few generations.

[nostrademons]

I picked it because it has the title "A meta-analytic review of longitudinal research". Meta-analyses are often a good way to summarize existing results in a field and get a quick overview of the actual data that's been produced. They tend to be less biased than cherry-picking an individual study, though it's impossible to eliminate all bias altogether.

The 5000-feet summary of the paper's results was that there is widespread consensus that there is a correlation between intelligence and education/occupation/income levels, but there are divergent results as to the magnitude of that correlation, ranging from .15 to .40 (a correlation of 0 indicates that the two variables are completely uncorrelated, 1.0 indicates they are completely dependent).

"It's controversial because it could be used to justify a number of racial or eugenic policies, and because it's sort of silly, in the melting pot of America, and with our knowledge of intelligence, to make any claims on social classes having stratified into different classes of human within the space of a few generations."

This is not how facts work. Something is true or false regardless of whether we like it, and regardless of the implications of its truth or falsehood. This is usually called the is-ought problem:

http://en.wikipedia.org/wiki/Is-ought_problem

A statement about how the world is - say, intelligence is correlated with income - is very different from a statement about how the world ought to be - say, that smart people ought to make more money than dumb people. It's very possible to believe the former and reject the latter. But your rejection of the latter has no bearing on the truth of the former: just because you don't like the conclusions that other people draw from a statement like "income and intelligence are highly correlated" doesn't make it untrue.

[jbooth]

Sigh.

Ok, Mr. Social Darwinist. Keep taking your medium-weak correlative effect and calling it a "fact".

On correlative effects. NFC winning the super bowl leads to an increase of the stock market the following year, with a predictive power of 80%, or .8 by your notation: http://www.snopes.com/business/bank/superbowl.asp. Obviously this has weaker causal power than genetic inheritance, which likely has some. But the numbers don't bear that out. Any presumption that rich parents means smart kid is exactly that.

If you're treating a weak correlative effect as a fact, you're the one engaging in the wrong side of the "is-ought" argument, and you're doing it to invoke "ought" on a particularly noxious view, to boot.

[yummyfajitas]

Intelligence is both heritable and correlated with wealth. So yes, parental intelligence can cause both wealth and child intelligence, leading to a correlation between parental wealth and child intelligence.

[barrkel]

Genetic determinism isn't so clear, unfortunately. Humans having two legs is highly genetically determined, but that doesn't mean that variance in the number of legs is explained by genes; it's more likely to be environmental factors, like injuries.

Another factor is reversion to the mean. Two bright people are likely to have children dumber than them.

[nostrademons]

He said correlation, not determinism. It's quite possible for wealthy parents to have smart children on average and yet for any given child of smart parents to be spectacularly dumb. (I know a couple myself, FWIW.)

Something with two legs is far more likely to be human than insect, for example, even if you do have the odd human with only one leg.

[yummyfajitas]

I didn't say it was genetically determined, I said it was heritable.

Regression to the mean occurs if the two bright people were bright by chance. This is not necessarily the case.