Originally Posted by indigo
Originally Posted by GGG
Is this a real world correlation?
Here is one example of a simple chart commonly referenced: http://vcbconsulting.com/gtworld/iqgrade.html

Knowing an IQ score can allow prediction of achievement. However the corollary is not considered to be true; Knowing achievement is not said to be predictive of an IQ score.

That chart is way way off. That's the problem with ratio IQs.
Originally Posted by aeh
Let me just remind everyone that grade levels ahead based on being able to do work from actual courses, and grade levels ahead based on grade equivalents from a standardized achievement test are two very different propositions, only one of which has significant validity--and it's not the one from the NRT.

And yes, the developmental arc for reading is very different from that for mathematics, and less dependent on access to direct instruction. (One of the reasons not to lean too heavily on grade equivalent scores is the early plateau in reading decoding raw scores.) The change in slope across the lifespan for academic growth also means that 2-3 years ahead at one point in time has a very different meaning from 2-3 years at another point.

Plus, in mathematics, pretty much the whole continent of North America is about 1-2 years behind the rest of the industrialized world, which I don't think is due to the population being a standard deviation lower than the rest of the world in intelligence (though there are moments when that seems rather plausible!).

IMO, they spend all that time on memorising coin names (US coins have no denomination printed on them, and much of the first three years mathematics is spent identifying them by sight), faffing about with inches and pounds and such, and spending waaay too much time on fractions due to the aforementioned medieval measuring system.