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Commonly Unrecognized Error Variance in Statewide Assessment Programs: Sources of Error Variance and What Can Be Done to Reduce Them

This report summarizes the Phillips' work on commonly unrecognized sources of error variance (or random variations in assessment results) and provides actions states can take to identify and reduce these errors in existing and future assessment systems. These "errors" are not mistakes in the traditional sense of the word, but reflect random variations in student assessment results.  Unlike the technical report by Phillips on which it is based, this report is written for policymakers and educators who are not assessments experts. It provides an explanation of the sources of error variance, their impact on the ability to make data-based decisions with confidence, and the actions states and their contractors should take as quickly as is feasible to improve the accuracy and trustworthiness of their state testing program results.