What is true about the distribution of IQ scores?

Approximately 95\% of the population has IQ scores between 70 and 130. Approximately 99.7\% of the population has IQ scores between 55 and 145. Only approximately 0.3\% of the population has IQ scores outside of this interval (less than 55 or higher than 145).

How is IQ distributed in a population?

IQ refers to mental age divided by chronological age, and multiplied by 100. IQ scores are distributed in such a way that the IQ scores of most people tend to fall in the middle range of the distribution. Most people show a moderate level of performance i.e. in the middle range of the distribution.

Is IQ normally distributed?

Not exactly. IQ tests are constructed to have a mean of 100 and an standard deviation of 15. However, they are not exactly normally distributed (although they are close). There is some evidence that the tails are fatter than normal and there is a right skew to the distribution.

Why are test scores normally distributed?

Normal curve distributions are very important in education and psychology because of the relationship between the mean, standard deviation, and percentiles. In all normal distributions 34 percent of the scores fall between the mean and one standard deviation of the mean.

What is the standard deviation of IQ?

15
An IQ test score is calculated based on a norm group with an average score of 100 and a standard deviation of 15. The standard deviation is a measure of spread, in this case of IQ scores. A standard devation of 15 means 68\% of the norm group has scored between 85 (100 – 15) and 115 (100 + 15).

Why is the IQ of 92 so low in southern Europe?

The lower IQ of 92 (range 90 to 94) in Southern Europe is attributable to some gene flow between South Asians (MENA) and Europeans across the Dardanelles Strait and the Aegean and production of an hybrid population in the Balkans whose IQs are intermediate between that of Europeans (99) and that of South Asians (84).

What is the distribution of IQ tests?

IQ tests are designed to conform to a Bell Curve distribution. This means if you graph them, they make a nice shape that is high in the middle and tapering on both ends that looks a bit like a bell as you can see in the visual distribution of the IQ scale below for the Wechsler Intelligence Scale distribution.

Which country has the highest IQ in the world?

Often surprisingly, but scientifically proven, a warmer climate has a markedly bad influence on the intelligence quotient. With an average IQ of 98 points, the USA ranks 27th in this ranking. With 108 points, the inhabitants of Singapore reach the highest intelligence quotas worldwide.

Where do the intelligence quotients by countries come from?

The intelligence quotients by countries are taken from the studies conducted by Richard Lynn and Tatu Vanhanen (2002), Heiner Rindermann (2007), Khaleefa and Lynn (2008), Ahmad, Khanum and Riaz (2008), Lynn, Abdalla and Al-Shahomee (2008), Lynn and Meisenberg (2010) as well as the PISA tests in 2003, 2006 and 2009.