How to Co-Create: A Compendium of Methods for Co-Creating Solutions to Complex and Wicked Problems in Public Health

Background: Co-creation has become a vital approach in public health, engaging diverse stakeholders, including vulnerable and marginalized populations, to collaboratively design and implement interventions and policies. By involving these groups directly, co-creation seeks to enhance health solutions' relevance and effectiveness. Despite increasing interest, the field of co-creation is fragmented, lacking a standardised approach for its design and application. Challenges such as inconsistent terminology and insufficient synthesis hinder the establishment of best practices, risking the potential of co-creation to be tokenistic. To make co-creation trustworthy and evidence based there is a need for methods that uphold its principles. However, there is limited research on methods. It is often unclear which methods are most appropriate, how these methods impact the co-creation process, whether they truly operationalise co-creation principles, and which methods are best suited to various contexts and populations. Evidence-based co-creation, especially within complex health research, requires a more structured and adaptable approach, integrating both quantitative and qualitative insights. Methods: This thesis contributes to addressing these gaps by systematically investigating methods for co-creation. It seeks to provide a structured resource that helps researchers and practitioners successfully select and apply co-creation methods, to support the development of impactful, equitable, and contextually relevant public health interventions. This thesis sought to advance the understanding and application of co-creation methods in public health by addressing several key objectives. First, it curates and synthesises existing literature to establish a comprehensive database of co-creation studies (Study 1). Building on this foundation, the thesis develops a taxonomy for organising methods, enabling structured selection (Study 2). Utilising data science methods, this study sourced methods from both academic and grey literature (Study 3) and investigated methods-specific literature as a means to source descriptive characteristics, application with various target populations, and the benefits and challenges of co-creation methods. (Study 4). Additionally, this thesis explored the dynamics of individual versus collective engagement in co-creation culminating in the development and validation of the Co-Creation Rainbow framework. This framework serves as a practical tool for assessing method alignment with co-creation principles, supporting thoughtful and informed decision-making in method selection (Study 5). Results: The findings of this thesis provide an in-depth analysis of co-creation methods, revealing substantial diversity in approaches across academic and practitioner sources. Study 1 established a foundational database of 13,501 co-creation studies, while Study 2 organised these methods within a taxonomy that includes facets such as participation level, context, and target population, enhancing method selection based on specific needs. Study 3 highlighted a wealth of methods, sourcing 956 methods. Study 3 also uncovered significant differences in methodological preferences, with academics tending towards qualitative approaches, while practitioners often employed more creative, participatory methods. Study 4 sourced an additional 248 co-creation methods, with these methods being applied across 40 target populations (e.g. engaging children, adults, and marginalized groups). The thematic analysis revealed nine benefits (Collaboration and Participation; Empowerment and Agency; Innovation and Creativity; Well-being and Satisfaction; Communication and Transparency; Flexibility and Ease of Use; Impactful and Valid; Reflection and Understanding; and Efficient and Strategic) and six challenges (Engagement and Participation; Resources and Practical Constraints; Trust and Transparency; Methodological Limitations; Systemic and Structural Barriers; and Focus and Commitment), highlighting the complexity and diversity of co-creation in public health research. Study 5 examined the role of individual versus collective engagement, demonstrating the importance of method adaptability in fostering meaningful collaboration by creating and validating the Co-Creation Rainbow framework. This framework categorises methods along an Individual-to-Collective Continuum and across dimensions of engagement, participation, and empowerment, providing a practical tool for aligning methods with co-creation principles. Together, these results culminate in a compendium of co-creation methods, serving as a resource for researchers and practitioners to approach co-creation as a structured, evidence-based methodology for designing and implementing co-creation processes across diverse public health contexts. Conclusions: This thesis contributes to a paradigm shift in co-creation, advocating for its recognition as a structured, evidence-based methodology rather than simply an action verb, or the tokenistic involvement of stakeholders in collaborative processes. The findings of this thesis substantially strengthen the methodology of co-creation by investigating methods, revealing the types of methods that can be used and their impact on the co-creation process. Moreover, this thesis bridges theory and practice by providing actionable tools to support co-creation. By addressing a critical gap in understanding and applying co-creation methods, this work not only advances academic discourse but also offers a comprehensive resource for future research and practice in public health. The systematic compilation and categorisation of nearly 1,000 co-creation methods, combined with the development of the Taxonomy of Co-Creation Methods and the Co-Creation Rainbow framework, provide a robust foundation for method selection, evaluation, and implementation in diverse contexts. These tools empower researchers and practitioners to design co-creation processes that are evidence-based, contextually relevant, and aligned with co-creation principles. The practical implications of this research are far-reaching. This thesis has the potential to enhance public health interventions and reduce health disparities by enabling informed decision-making about method selection and fostering systematic, inclusive and impactful co-creation processes. The open-access resources developed as outputs of this research ensure that the thesis’ contributions are widely accessible. This accessibility supports the operationalisation of co-creation as a trustworthy and robust methodology, ensuring that methods are not only evidence-based but also impactful. This work also highlights the need for continued research, innovation and collaboration in the field of co-creation. As public health challenges grow increasingly complex, the datasets, tools and framework developed here provide a foundation for evolving and expanding co-creation practices. By bridging gaps between theory and practice, this research lays the groundwork for the global co-creation community to refine methods, address emerging challenges, and drive transformative change in public health. Equipping researchers and practitioners with the actionable resources and insights generated in this thesis champions a future where co-creation is a robust methodology for generating innovative, inclusive, sustainable and effective public health solutions.