Well this is pretty bad "science", its a voluntary test that is only accessible in English, where the subjects taking the test are coming on their own to it while knowing what the test is about, and it has vastly different data points, like Sweden has over 5000 data points for a population of 10 million, while Spain has a 2000 data points for a population of 46 million.
Technically speaking even the area where the test is being taken isn't verified, but that is really a minor thing in comparison.
Technically speaking even the area where the test is being taken isn't verified, but that is really a minor thing in comparison.