How to use quantitative and qualitative frameworks in whole systems research: detailed examples from two mixed-methods case studies

Introduction Evaluating complex interventions such as complementary and alternative medicine (CAM), including traditional Chinese medicine (TCM), requires approaches that capture both context and outcomes. Whole systems research (WSR) employs mixed-methods designs to study these systems in real-world settings. Methods We highlight key methodological considerations for mixed-methods data collection and analysis, illustrated by two case studies: (1) a randomized controlled trial with an embedded process evaluation of spiritual healing for moderate depression; and (2) a cross-sectional survey of oncology providers with written comments (n = 157). Results In Case 1, spiritual healing showed potential benefit for adults with moderate depression. Adherence was high, with minimal dropout and timely questionnaire completion; the process evaluation linked this to close follow-up by the study nurse. In Case 2, communication about CAM differed across provider groups: CAM providers promoted integration with conventional care; physicians were more skeptical, citing limited efficacy evidence; and nurses expressed more positive attitudes. CAM providers and nurses favored strengthening communication between CAM and conventional providers, whereas physicians were less supportive. Qualitative comments enriched and contextualized these patterns. Conclusion Integrating qualitative contextual insights with quantitative outcomes yielded more comprehensive evidence than either method alone, enabling the operationalization of WSR. The detailed procedures for data collection and analysis provide a practical template for students and researchers new to mixed-methods research.