[3] This gap between reported and unreported crimes calls the reliability of official crime statistics into question, but all measures of crime have a dark figure to some degree.
Comparisons between official statistics, such as the Uniform Crime Reports and the National Incident-Based Reporting System, and victim studies, such as the National Crime Victimization Survey (NCVS), attempt to provide an insight into the amount of unreported crime.
[4][5] Self-report studies are also used in comparison with official statistics and organized datasets to assess the dark of crime.
[3] The gap in official statistics is largest for less serious crimes.
[3] Estimates of sexual violence from victim surveys differ from sexual violence crime statistics reported by law enforcement.