Open Thread: July 2010

komponisto

This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.

Part 2

This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.

Part 2

I think this is one of the few cases where Shalizi is wrong. (Not an easy thing to say, as I'm a big fan of his.)

In the second part of the article he generates synthetic "test scores" of people who have three thousand independent abilities - "facets of intelligence" that apply to different problems - and demonstrates that standard factor analysis still detects a strong single g-factor explaining most of the variance between people. From that he concludes that g is a "statistical artefact" and lacks "reality". This is exactly like saying the total weight of the rockpile "lacks reality" because the weights of individual rocks are independent variables.

As for the reason why he is wrong, it's pretty clear: Shalizi is a Marxist (fo' real) and can't give an inch to those pesky racists. A sad sight, that.

cousin_it:

A sad sight, that.

Indeed. A while ago, I got intensely interested in these controversies over intelligence research, and after reading a whole pile of books and research papers, I got the impression that there is some awfully bad statistics being pushed by pretty much every side in the controversy, so at the end I was left skeptical towards all the major opposing positions (though to varying degrees). If there existed a book written by someone as smart and knowledgeable as Shalizi that would present a systematic, thorough, and unbiased analys... (read more)

4[anonymous]16y

Your analogy is flawed, I think. The weight of the rock pile is just what we call the sum of the weights of the rocks. It's just a definition; but the idea of general intelligence is more than a definition. If there were a real, biological thing called g, we would expect all kinds of abilities to be correlated. Intelligence would make you better at math and music and English. We would expect basically all cognitive abilities to be affected by g, because g is real -- it represents something like dendrite density, some actual intelligence-granting property. People hypothesized that g is real because results of all kinds of cognitive tests are correlated. But what Shalizi showed is that you can generate the same correlations if you let test scores depend on three thousand uncorrelated abilities. You can get the same results as the IQ advocates even when absolutely no single factor determines different abilities. Sure, your old g will correlate with multiple abilities -- hell, you could let g = "test score" and that would correlate with all the abilities -- but that would be meaningless. If size and location determine the price of a house, you don't declare that there is some factor that causes both large size and desirable location!