One purpose of administrative data is to support evidence-based policymaking. With good data, policymakers can make decisions that improve the viability and effectiveness of public programs and policies. However, administrative data is sometimes insufficient when addressing key policy questions, because of varying data quality. This is in part because most administrative data is collected mainly for recording and reporting the use of public services, or for providing basic information about service users, rather than research. Due to this difference in purpose, administrative data can present particular problems when used for evidence-based policy research. Previous research examining the quality of administrative data has identified several key issues. In this report, as a state data and research agency, we address three commonly-found errors - reporting, nonresponse and measurement, using a research project that Washington’s Education Research and Data Center (ERDC) is conducting.