Expected IQ spread on a jury
A blog post examines the expected IQ spread among members of a jury, relating it to discussions about how large IQ differences can hinder communication between people.
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In a randomly selected jury of 12 people, the expected highest IQ is about 117 and the lowest about 83, giving a spread of roughly 34 points, based on a normal distribution with mean 100 and standard deviation 15.
The article discusses how to calculate the expected range for samples from a normal distribution, explaining that the expected range depends on sample size and is expressed as a constant multiple of the standard deviation. It presents tables and approximations for these constants, known as d₂ values, which are used in quality control and statistical process control.