Frankel and Wallen (2003) and Yin (2003) noted that evidence from multiple case studies
was generally more convincing compared to that from a single case study and could lead to
useful and valid generalisations.
Over a period of 6 months, evidence gathered from the multiple case study was
supported by evidence from a General Sample of students, this consisting of the remaining
students in the six classes from which the case study students were drawn. In order to
ensure the validity of the data, and increase the possibility of making reasonable
generalisations from the results of the study, data triangulation was achieved using multiple
sources of evidence, as shown in Table 1.