The National Crime Victimization Survey (NCVS) Knowledge Corner provides quick tips and explanations for NCVS data users on a variety of topics. In this video, BJS Statistician Susannah Tapp, PhD, describes item nonresponse in the NCVS. Item nonresponse results in missing data. She discusses the four missing data codes used in the NCVS: residue, out of universe, item invalid until, and item invalid after. For more information, please visit https://bjs.ojp.gov/programs/ncvs or email us at [email protected].