by Savia » Sun Mar 09, 2008 3:52 pm
That is a definition of IQ; it's not the only one. For example, the standardised IQ test used by most psychologists is a normalised distribution that uses Z-scoring to give a population with a mean IQ of 100 and a standard deviation of 15. So about 2/3s of people have an IQ in the 85-115 range, and about 99.8% fall between 55 and 145. MENSA generally accepts the top 2% for membership- about 135 and up.
Furthermore, modern IQ tests (Stanford-Binet et al) consist of a battery of separate tests that are added to the battery iff they have a statistically significant correlation with scores on the other tests. So for example there's a general knowledge section in there- why? Because general knowledge correlates with the other test scores so, the story goes, it measures the same underlying factor- which is known as 'G' or the General Intelligence.
Other models, such as Howard Gardner's Multiple Intelligences, divide intelligence into categories and score separately in each. Sadly these categories are mostly defined by What Howard Gardner Thinks They Should Be.
In my opinion the reason that middle class caucasian males tend to do better on IQ tests is that they are overwhelmingly designed by middle class caucasian males. It's a systemic error in the whole thing.
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