Frequently Asked Questions (FAQs) about giftedness
What exactly is IQ?
The intelligence quotient—abbreviated IQ—is a measure of how a person’s intelligence can be described in relation to a group of people who are representative of that person. In the case of IQ, the average of this reference group is always set at 100; therefore, the average IQ is an IQ of 100. IQ scores are also considered to have a normal distribution. This means that most people in the reference group (68 percent) have an IQ between 85 and 115. This area is also referred to as the average range. About 95 percent of the people in the reference group have an IQ between 70 and 130. Extremely low or high IQ values are equally rare: Around two percent of people have a very low IQ (below 70) and about two percent have a very high IQ (above 130).
Besides the IQ norm, other test norms such as value points or T-scores can be considered. These norms can all be converted to one another. The difference between them is in the respective average value that has been applied and in the specification of the average distribution of the values. For example, the average value for T-scores is 50 (thus corresponding to an IQ of 100), and the average range is between 40 and 60. Similarly, percentile ranks are also used. The percentile rank indicates the percentage of the comparison group that performed worse or at most equally well on the same test. For example, being ranked in the 98th percentile means that only two percent of the comparison group performed better than the subject on the test. This value corresponds to an IQ value of 130.