A case study is a specific instance that is frequently designed to illustrate a more general principle (Nisbet and Watt 1984: 72), it is ‘the study of an instance in action’ (Adelman et al. 1980) (see http://www.routledge.com/textbooks/ 9780415368780 – Chapter 11, file 11.1. ppt). The single instance is of a bounded system, for example a child, a clique, a class, a school, a community. It provides a unique example of real people in real situations, enabling readers to understand ideas more clearly than simply by presenting them with abstract theories or principles. Indeed a case study can enable readers to understand how ideas and abstract principles can fit together (Nisbet and Watt 1984: 72-3). Case studies can penetrate situations in ways that are not always susceptible to numerical analysis. As Robson (2002: 183) remarks, case studies opt for analytic rather than statistical generalization, that is they develop a theory which can help researchers to understand other similar cases, phenomena or situations.