Fig. 1.

Within-country gaps in mean early literacy test scores (reference category = Q3). Error bars are 95 % confidence intervals. Q1 to Q5 refer to income groups defined by the quintile boundaries of the U.S. distribution from lowest to highest; that is, Q1 is the group with income less than $27,000, and Q5 is the group with income greater than $96,000. The chart plots the gap in mean standardized test scores between the specified group and the middle Q3 group (families with incomes of $44,000–$65,000 equivalized, in 2011 U.S. dollars). Estimates are calculated from the underlying microdata separately for each country. See Tables 1 and 2 for details of the source samples.