A self-report study is a way of measuring or studying crime where people (normally a small number in a focus group) are asked to talk about crimes that they have committed. The nature of the study means that they often produce useful data about anti-social behaviour and "petty crime" but it is unlikely to reveal much about more serious crimes that people are unlikely to self-report. Furthermore, if the study is done with a group of young people there is the danger that peer pressure will make the results less valid.