because the data in these reports are based on reported crimes, they share the same measurement problems that have been listed above. There are a number of errors in the UCR. First, the UCR does not try to count all reported crimes. Index offenses, also called Part I crimes, are only counted if they are reported AND recorded by police. Usually, there are always reports of crime, but police may choose not to record them for a number of reasons. Also, the UCR will not include Part II crimes only if the arrestee has been formally charged with a crime, because individual states may have varying definitions of these crimes (Maxfield 113). Another source of error is created by the hierarchy rule used by police agencies, which basically means that if a number of crimes are committed in one incident, to only count the most serious one in the UCR. However, do not think that the UCR is not helpful. UCR data represents groups of analysis, meaning that crime reports are available for cities and states; the data just does not represent individual crimes very well. Asking people if they have been victims of crimes is a good way to measure data. This type is usually done in the form of a survey. Surveys can possibly have several advantages, like: obtaining information that has not been reported to authorities; finding out about crimes reported to police, but not recorded officially; and can provide data on victims and offenders and the incident themselves (Maxfield 115). An example of this is the National Crime Victimization Survey, or NCVS for short. The NCVS yields more data on individual victims, offenders, and incidents, meaning its better used for studies on individual factors in crime victimization. This is because it is a survey designed to represent nationwide levels of crime, but cannot provide crime estimates for cities or states (Maxfield 116). Surveys of offenders are used just like victimization surveys, but these are for the offenders. The surveys often measure how many crimes the offender has committed. This type is helpful especially for victimless crimes, like prostitution, public order and delinquency crimes, and rarely reported crimes, like shoplifting. As with all surveys, there are some problems one may run into, such as dishonesty in responses and exaggeration, but these surveys help us to find out some data that would otherwise never be noted. Because crime