"A child's learning is the funtion more of the characteristics of his classmates than those of the teacher." James Coleman, 1972

Thursday, September 10, 2009

New Census Data Confirms the Rich Getting Richer and Everyone Else, Poorer

Much has been written about the relationship between SAT scores and test-takers’ family income. Generally speaking, the wealthier a student’s family is, the higher the SAT score.

Let’s take a look at how income correlated with scores this year. About two-thirds of test-takers voluntarily report their family incomes when they sit down to take the SAT. Using this information, the College Board breaks down the average scores for 10 income groups, each in a $20,000 range.

First, here are the individual test sections:

SAT reading scores by incomeSource: College Board

SAT math scores by incomeSource: College Board
SAT writing scores by incomeSource: College Board

Here are all three test sections next to each other (zoomed in on the vertical axis, so you can see the variation among income groups a little more clearly):

SAT scores by income class
Source: College Board

A few observations:

  • There’s a very strong positive correlation between income and test scores. (For the math geeks out there, the R2 for each test average/income range chart is about 0.95.)
  • On every test section, moving up an income category was associated with an average score boost of over 12 points.
  • Moving from the second-highest income group and the highest income group seemed to show the biggest score boost. However, keep in mind the top income category is uncapped, so it includes a much broader spectrum of families by wealth.

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