## Wednesday, November 16, 2011

### Predictive power of early childhood IQ, part 2

I came across this table in Intelligence by N. Brody. Berkeley Growth Study (61 participants).

See earlier post predictive power of early childhood iq.

#### 10 comments:

David Coughlin said...

I don't like that range of changes.  Everyone gets smarter as they get older?

steve hsu said...

I believe they are giving you magnitudes of changes, not the sign.

Christopher Chang said...

Yup, too bad the lower magnitude bound is a pretty useless piece of information...

CautiousProgressive said...

Steve, are you familiar with the research showing (or claiming to show) that self-control correlates significantly more to academic and career performance, than IQ does?

(eg. the sources discussed in the following article pop-science article by The New Yorker: http://www.newyorker.com/reporting/2009/05/18/090518fa_fact_lehrer)

steve hsu said...

Search under "marshmallow experiment" on this blog. You'll find links to the original papers.

David Coughlin said...

I got that.  And I double down on what Christopher followed up with.

MtMoru said...

Not credible.

Take age 9 to 17. 5.7/15 = .38. So rho = sqrt(1-.38^2) = .923. Adjusted for reliability and the age 9 IQ should correlate perfectly with the age 17 IQ

For normalized n(0,1) data the slope of the regression line equals rho. So the mean change is greater than sqrt(2/pi), but it shouldn't be as large as it is.

MtMoru said...

That's all rot MtMoru.

"Because I care", here's what a little plug and chug give.

I. 2(1-r)(1-2/pi) = var(|test -retest|)

II. 2*sqrt((1-r)/pi)) = mean(|test - retest|)

So for age 9 estimated r is .8 using I and about .7 using II.

The two may not agree because the data are not actually sampling a biveariate normal distribution. I doubt it's sample bias or statistical +/-.

Robert Jackson said...

I graduated with a 4.0Gpa in Accounting then went into Computer Science before dropping out after 2.5 years I had a 3.98Gpa. I got one 95 in a class and the way the school calculated it dropped my Gpa by .02 I plan on going back to college to finish my degree in Computer Science, although I may switch to Electrical Engineering once I complete coding of the current website I am working on. I find both to be insanely interesting.

Robert Jackson said...

I am sure people who use their brain and think a lot manage to maintain their IQ for most of their adult life until older age just gets to you.