About the data
The test score data for third- through eighth-graders in traditional public school districts comes from the Educational Opportunity Project at Stanford. A report on the new data was released on May 13 by the Education Scorecard, a joint project by Sean Reardon at the Stanford group; Thomas Kane at the Center for Education Policy Research at Harvard; and Doug Staiger at Dartmouth.
Researchers linked state test results with the results of a federal exam, the National Assessment of Educational Progress, to allow for comparisons across states. States were excluded if they allowed families to opt out of tests, recently updated their tests or were otherwise missing data.
Researchers identified districts in the same state that were similar in size, demographics and type of community, such as urban, suburban or rural.
This tool includes data for medium and large districts where scores were available. For districts missing 2015 data, The Times used an average of 2014 and 2016 scores as a baseline.