The state auditor has advised education leaders that releasing delayed state report cards won't hamper his investigation into potential tampering with school attendance numbers. Auditor David Yost appeared today before the state's state school board. The panel postponed release of report cards last month. State investigators are examining reasons schools withdrew students and whether the withdrawals were legitimate. Removing poor students from the books can boost performance measures that determine government aid and improve school performance rankings. Yost says attendance tampering practices probably went on for years so this year's report cards will contain no more flaws than earlier ones. He has engaged Ohio State University statistics faculty to build a model for identifying reporting anomalies in statewide data. Irregular practices in Columbus, Toledo and suburban Cincinnati districts prompted the probe.