While Edison Schools has contracts with seven schools in Hawai'i this year, the model differs from the one analyzed by Rand Corp.

The Rand study looked at schools managed by Edison, which takes complete control over the schools' curricula, staff and assessment tools.

In Hawai'i, Edison employees are working with the schools' existing curricula and staff, with Edison's people providing teaching strategies and other professional development.

The Rand study indicated that Edison's strategies worked best when Edison was given the support and latitude needed to implement its own design, but the study's authors said that a partnership between Edison and the schools does not necessarily preclude student improvement.

Lead author Brian Gill noted that one of the strategies Edison is employing here, a diagnostic assessment system, has been highly commended by staff at the managed schools.

"This helps facilitate the role of principals as educational leaders, which we found helpful," he said.