The purpose of the SISTEM model is to create a proportional representation of real world populations and to simulate changes in the social identity of individuals resulting from actions taken by individuals and that leads to changes in affiliation and membership within different identity groups. Agents also engage in social actions that enhance groups to which they belong and degrade a targeted out-group. Identity groups that might be represented include both relatively fixed demographics e.g. gender, ethnicity, education and more dynamic affiliations e.g. political, social. An agents social identity may therefore consist of multiple identities across different groups that are considered influential in differentiating people within a population.