Last year, some 21 states and the District of Columbia opted to rank teacher-preparation programs by measures of their graduates’ effectiveness in the classroom, such as their value-added scores. But in a new article for Education Next, Paul von Hippel and Laura Bellows find that, when ranking programs on value-added, the differences between teacher-preparation programs are typically too small to matter. These differences are also almost impossible to estimate with any reliability, as estimation errors will often be larger than the differences researchers are trying to estimate. As a result, program rankings will consist largely of noise, which means that programs cannot be ranked in a meaningful order. Therefore, von Hippel and Bellows conclude, it’s not helpful to rank a state’s programs by teachers’ value-added scores and suggest that other measures of program quality might be used instead. To learn more about rating teacher-preparation programs, read the full article on EdNext.org.