Victimology offers, on the one hand, a picture of victims in which they may be held partially responsible for their own victimization; on the other hand, it offers analysis that helps understand the individual and environmental features that may contribute to being a victim of crime. The methods for data collection for policy development include national crime victimization surveys, methods of assessing impact on victims, and research into the experience of victimization. Research by Janoff-Bulman and Frieze suggests that psychological distress in victims results from the shattering of three basic assumptions: personal invulnerability; a perception that the world is meaningful and ordered (just world hypothesis); and the view of self that is positive. Davis (2003) observes that more than two-thirds of victims needing emotional support or practical help generally receive it from family and friends which is far more than that received from victim assistance programmes.