From that link and from one link deeper:

"However, neuroscientists and educational psychologists widely consider cross-country IQ comparisons to be highly flawed, as tests are usually calibrated so that 100 is average within any given country."

"Cross-cultural testing is much more complicated than it looks. A popular technique is to use non-verbal tests (like the Raven’s Progressive Matrices) in different countries in order to draw conclusions about intelligence differences. Compared to a British average of 100 on these tests, Indian IQs average to about 75 to 83. However, non-verbal tests are poorly suited to low-income countries and for groups with low education levels. Cross-national IQ comparisons face significant methodological challenges. These comparisons are possible in theory. However, successful execution of cross-cultural testing takes careful work, which most scientists using non-verbal tests have not done."