"There are two general types of self-report surveys: surveys of unknown offenders and surveys of known offenders. Surveys of unknown offenders provide information that has not made it into official police data. Surveys of known offenders may provide insight into the details of a criminal event including offender motivation, situational factors, and thoughts and feelings of the offender before, during, and after the event. Surveys of unknown offenders can be problematic in that respondents may not want to share information that they fear may be reported to police. Surveys of known offenders may not provide a completely accurate picture if offenders are fearful that the information could be used against them in some way. With both types of self-report surveys, results may not be valid and reliable because they depend on the offender’ memory of a criminal event, recall ability, and the extent to which the offender is willing to share information about the event. Furthermore, offenders may experience memory lapses or want to present themselves in a more positive light. In some cases, this may not even be a conscious decision because oftentimes people remember what they want to remember about an event, especially in recalling a criminal event in which the offender’s behavior may cause shame or embarrassment."