The modern IQ test uses a slightly different method than Binet's original design. These modern tests reference people against those of their own age rather than assign them a ratio as in the the traditional IQ Tests. The average IQ, however, remains 100.
It is thought that the main problem with the traditional IQ test is "intelligence" is not something easily measured but rather a combination of complicated and fluctuating factors both internal and external to the subject. Elements such as training, environment and the attitudes of those giving the test have been shown to impact a subject's results.
IQ tests have a reputation of being culturally biased, and this is generally believed to be true. Jonathan Rich, Ph.D., writing on the Psychological Testing website, observed, "Intelligence is always measured relative to a particular culture; 'culture free' tests of intelligence do not exist."