Longitudinal Multiple Case Study — Multi-Site Repeated-Wave Case Research

Longitudinal multiple case study is a qualitative research design that examines two or more bounded cases through repeated data-collection waves over an extended period. By tracking each case across time and comparing patterns across cases, researchers can document how phenomena change, stabilise, or diverge — generating both depth within each site and breadth across sites that neither a single case nor a one-shot survey can provide.