Researchers Debate Merits of ‘Value Added’ Measures

Much of the controversy about using value-added assessments to measure the effectiveness of schools and teachers involves the strengths and weaknesses of existing models for tracking individual students’ growth.

“We know that every model currently in use contains some amount of statistical bias, and these imperfections are not well understood,” Daniel Fallon, the chairman of the education division at the Carnegie Corporation of New York, said during a meeting on value-added assessment in Columbus, Ohio, last month.

Even though value-added methods should not be used in isolation, Mr. Fallon argued, “we should not let the desire to be absolutely right interfere with the progress we can make with...