Correlation between IELTS/TOEFL and Academic Performance

Just looked at a meta-analysis on IELTS/TOEFL scores and GPA ... and the correlation is weak! The audience is both unsurprised and surprised.

The meta-analysis looked at 32 different studies with 132 different effect sizes, stating that overall, "assessments had a weak positive correlation with academic achievement (r=.231, p<.001)"

That r value accounts for a roughly 5% variance in GPA, which is pretty weak compared to something like the ACT (ρ̂ ≈ .51, ~26% variance in GPA). The weakness of the correlation wasn't surprising to me at all, but the fact that there was a correlation at all is surprising.

English proficiency means you can read and write and understand the language of instruction but says nothing about a student's motivation, effort-level, etc. The authors call out the general skepticism of associating academic performance with GPA, but it is the mostly widely available, numeric association we have.

I wonder if the weak correlation is somewhat indicative of a student's ability to take tests rather than anything else, since GPA is essentially an average of a bunch of test scores, essays, etc. A much more interesting study that I wish someone would do is correlation of IELTS/TOEFL performance against GPA in major and breakout by area of study.