Citation: Kiernan, Nancy Ellen (2001). Reduce Bias with Retrospective Questions: Tipsheet #30, University Park, PA: Penn State Cooperative Extension. This document is part of a series of Tipsheets that contain practical evaluation illustrations based on current research and developed by Nancy Ellen Kiernan at Penn State Cooperative Extension. This document focuses on how to reduce bias with retrospective questions. Copyright 2001 The Pennsylvania State University#Survey #HowTo #Bias #ExtensionEducationEvaluation