A serious question. Doesnt IQ depend on people taking the test bothering to try? I'm becoming more skeptical that IQ as a scale, rather than rough rank, has much validity across cultures. A view I've changed in the last year.
Somehow people "just don't try" in exactly the proportions needed to have their resulting IQs wind up such that it predicts their life performance. Occam's butterknife. Look at the NFL wonderlic results - every player takes it.