Educational Attainment and Income (1991-2003)
Households with higher educational attainment are likely to have higher incomes than those with low educational attainment -- members of the lowest income bracket tend to have no more than a high school education, while the highest income bracket members tend to hold graduate degrees.
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"Educational attainment in the United States."
http://en.wikipedia.org/wiki/Educational_attainment_in_the_United_States%23Social_class_and_education
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