Saying that IQ measures g is like saying that flow through a mountain creek measures snowmelt. More of one generally means more of the other, but there’s a bunch of fiddly little details (maybe someone’s airlifting water onto a forest fire upstream, or filling their swimming pool) that add up to a substantial deviation—and there are still a lot of unanswered questions about the way they relate to each other.
In any case, g is more a statement about the correlations between domain skills than the causes of intelligence or the shape of the ability curve. The existence of a g factor tells you that you can probably teach music more easily to someone who’s good at math, but it doesn’t tell you what to look for in a CT scan, or whether working memory, say, will scale linearly or geometrically or in some other way with IQ; those are separate questions.
g was observed as a correlation between test scores. That is by definition a scalar value, but we don’t know exactly how the underlying mechanism works or how it can be modeled; we just know that it’s not very domain-specific. It’s the underlying mechanism, not the correlation value, that I was referring to in the grandparent, and I’m pretty sure it’s what ialdabaoth is referring to as well.
Saying that IQ measures g is like saying that flow through a mountain creek measures snowmelt. More of one generally means more of the other, but there’s a bunch of fiddly little details (maybe someone’s airlifting water onto a forest fire upstream, or filling their swimming pool) that add up to a substantial deviation—and there are still a lot of unanswered questions about the way they relate to each other.
In any case, g is more a statement about the correlations between domain skills than the causes of intelligence or the shape of the ability curve. The existence of a g factor tells you that you can probably teach music more easily to someone who’s good at math, but it doesn’t tell you what to look for in a CT scan, or whether working memory, say, will scale linearly or geometrically or in some other way with IQ; those are separate questions.
g is an unobserved value, a scalar. It cannot say anything about “causes of intelligence” or shapes of curves. It doesn’t aim to.
g was observed as a correlation between test scores. That is by definition a scalar value, but we don’t know exactly how the underlying mechanism works or how it can be modeled; we just know that it’s not very domain-specific. It’s the underlying mechanism, not the correlation value, that I was referring to in the grandparent, and I’m pretty sure it’s what ialdabaoth is referring to as well.
To be more precise, the existence of g was derived from observing the correlation of test scores.
Moreover, g itself is not the correlation, it is the unobservable underlying factor which we assume to cause the correlation.
It is still a scalar-valued characteristic of a person, not a mechanism.