# To what extent does AFQT correlate with IQ?

Wikipedia has a pretty non-informative page as to the nature of the (US) Armed Forces Qualification Test (AFQT) as it mostly talks of results ranges etc. What I could descipher from there is it that it has three (or maybe four, depending on how one counts) [sub]parts,

• Arithmetic Reasoning (AR) – 30 questions in 36 minutes
• Mathematics Knowledge (MK) – 25 questions in 24 minutes
• Verbal Expression (VE)= (WK)+(PC)
• Word Knowledge (WK) – 35 questions in 11 minutes
• Paragraph Comprehension (PC) – 11 questions in 22 minutes

and

The formula for computing an AFQT score is: AR + MK + (2 x VE).

That sounds a bit like SAT... and a quick search found one paper that talks of "cognitive skills as measured by the AFQT". (SAT is pretty well correlated with IQ.) So, to what extent does AFQT correlate to more traditional IQ [sub-]scores?

• It is worth noting that the most commonly used IQ tests don't even correlate perfectly with themselves. Or said in another way, of course there is always some measurement error. A good IQ test may have test-retest correlation of $r = 0.9$, and hence the correlation of $0.8$ is actually an underestimation of the strength of the relation between IQ tests and the AFQT, because some of that remaining $1-0.8 = 0.2$ is simply measurement noise.