We used the National Assessment of Educational Progress (NAEP) to gauge each state’s academic performance. NAEP is given to a representative sample of students in all 50 states and the District of Columbia. We compared the percentage of students scoring in the top two achievement levels (proficient and advanced) across states in math and reading in grades 4 and 8 on the most recent (spring 2013) administration of the exam.
We used these numbers in two calculations. First, we averaged the percentage of students scoring proficient or advanced across tests and subjects to create a single average for all students in those grades in the state. Second, we measured the change in the percentage of students scoring proficient or advanced from the 2005 administration of the exam—the data used for the first Leaders & Laggards publication—to 2013. We averaged those scores across grades and exams and combined them with the absolute level of proficiency from 2013 to create an overall NAEP index score. We then ranked the index scores and awarded A’s to the top 10, B’s to the next 10, C’s to the middle 11, D’s to the next 10, and F’s to the bottom 10.