Study: Rural Chinese score 88.95 on the Raven’s non-verbal IQ test, over one standard deviation lower than the commonly cited Chinese IQ of 105. Study also finds that IQ was a better predictor of math achievement than all environmental and demographic variables. So, the theory that Chinese average IQ is overinflated due to biased sampling turned out to be true.
Source:
https://www.sciencedirect.com/science/article/abs/pii/S10 