Study Questions Reliability Of Single-Year Test-Score Gains

By Lynn Olson

Washington

More than half the states reward or punish schools based largely on test scores. But a new analysis suggests the methods used to identify good and bad schools are far less reliable than state policymakers may think.

The study, which will be published next year, found that between 50 percent and 80 percent of the improvement in a school's average test scores from one year to the next was temporary and was caused by fluctuations that had nothing to do with long-term changes in learning or productivity.

"This is a paper that's well worth going through and understanding," said David W. Grissmer, a senior management scientist in Washington for the RAND Corp., a Santa Monica, Calif.-based research organization. "The question is, are we picking out lucky schools or good schools, and unlucky schools or bad schools? The answer is, we're picking out...