In the Washington Post Answer Sheet blog, Gary Miron, professor of education at Western Michigan University, questions whether the AJC investigation into test score disparities nationwide considered student mobility.
Reporter Heather Vogell, a member of the AJC investigative team into test scores, responds here to that concern:
By Heather Vogell
Some school district officials and education consultants have raised the issue of whether high student mobility would lead a district to be highlighted in our analysis even if they had no cheating problem.
A high rate of mobility is a characteristic of virtually all inner city high-poverty districts. If it were true that our methodology just flagged mobility instead of potential cheating, then you would expect all urban districts with high mobility to be flagged.
This was not the case. For example, Cleveland schools, with a better than 30 percent mobility rate, had an average 4 percent of classes flagged by our analysis in 2008-2011. Statewide, about 5 percent of classes were flagged in those years. Chicago, Fresno and Amarillo, Tx., are other examples of districts grappling with high mobility which did not have high concentrations of suspect scores.
Before publishing the analysis, we also looked for large changes in the percentage of poor students. They were so rare we did not eliminate any data because of them. We also looked for changes in the number of students in a grade that were greater than 25 percent, suggesting a massive change at a school. We did remove from our data those with such big changes, which amounted to about 6 percent of classes.
University of Georgia statistics professor Jaxk Reeves, who is also director of the Statistical Consulting Center, reviewed the AJC’s analysis and said that absent a radical change in the makeup of a school — such as a sudden, large influx of poor or wealthy students — mobility should not have a major impact on how a district fares in the analysis.
Atlanta school district officials also raised this issue when the AJC first began analyzing their scores. The newspaper took an in-depth look at student mobility in Atlanta and in other, similar districts nearby. It showed that the other districts did not have nearly the same concentration of suspicious scores as Atlanta, despite having similar populations of students
–From Maureen Downey, for the AJC Get Schooled blog