FIGURE 8.4 Effects of intelligence and education on income Intelligence influences income, but so do other factors, such as education. These data indicate the average income of people who received different levels of education and who scored in different quintiles (fifths) of the IQ distribution. Within any given educational level, people with higher IQ scores earned more. Thus, among people with only a high school education, those who scored in the bottom 20% on an IQ test (the blue bar) averaged only a little more than $250/week, but those who scored in the top 20% (the purple bar) averaged almost $450/week. People in the top 20% in IQ score earned considerably more, but here too education mattered: those with high IQ scores who had only a high school education earned an average of roughly $450/week, whereas those with comparable IQ scores and a four-year college education earned almost $650/week. (Data from Ceci, 1996)