reliability And validity of IQ tests
There are different categories, sub-categories and series of IQ tests that have ben developed over time by highly recognised bodies. Each of these carries their own pro, cons, biases as well as predetermined target audiences. However, the discussion here focuses on general IQ tests available online.
Reliability by definition requires similar outcomes to be presented repeatedly when other conditions are controlled same. Standardized IQ tests historically do provide similar outcomes in general, thus having high reliability. Even though because the controlling valuables are impossible to maintain, the results can differ. Which means due to the inherent nature of the brain, and varying mental states, same person can receive different scores at different times. Motivation, anxiety and other outside influences such as the climate and surroundings can affect the score. This requires all IQ tests to have an estimated standard error similar to all statistical quantities.
Validity in IQ tests refer to the accuracy and applicability of the results to the notion of human intelligence. This is an inherent stigma attached with the subject of IQ. The vast majority of researchers, scholars on the field do agree that IQ tests will not account for general intelligence. It is very well conveyed that, IQ score is much more co-relevant to academic performance and provide little to no indication of social intelligence. Broadly, it is irrefutable that IQ tests have high statistical validity and serve many purposes related to intelligence.
The IQ test used in Brain Ranking
Currently the Mensa Norway IQ test has been used as the measurement of ranking. This can be found at https://test.mensa.no/
Mensa is one of the most renowned bodies in recent IQ societies. Their supervised IQ tests are considered to be the gold standard in modern times. There are many practical hurdles in finding a reliable IQ test which can be done online and without any registration. Many of the online tests you can find with a simple search are by far up to any standard. Hence, the above was chosen after careful consideration of many related factors. Also, we encourage all of you to research on this particular test and confirm the standard provided.