Author: Dr Oliver Hamer and Dr Jade Thomson, Postdoctoral Research Fellow and Postdoctoral Research Assistant in Evaluation within the Evaluation & Policy Analysis Unit at Edge Hill University, Northwest England, UK.
Complex programmes rarely create change in simple or predictable ways. In this article, Dr Oliver Hamer and Dr Jade Thomson examine how Ripple Effect Mapping can help evaluators capture intended and unintended impacts, strengthen shared learning, and better understand how change emerges within complex systems.
When change moves in unexpected ways
Evaluating complex programmes and interventions is rarely straightforward. Those working to evaluate programmes which span across multiple systems (e.g., place-based initiatives) will resonate with this, as interventions do not often operate in isolation. Furthermore, the impact of these programmes is rarely linear, and meaningful change frequently emerges in unexpected ways. Evaluation can, however, default to assessing predefined outcomes, meaning that evaluators may miss important effects and misunderstand how change happens within complex systems. Complex public health challenges (e.g., obesity, diabetes, and health inequalities) are now widely understood as products of multifaceted adaptive systems1. Within these systems, outcomes regularly emerge through interactions and feedback loops which may be delayed or unintended2. As a result, focusing narrowly on evaluating predefined outcomes is often of limited value, as there is a need to understand how and why change occurs, as well as what changes (a realist evaluation lens)3,4.
Following the ripples, not just the outcomes
Ripple Effect Mapping (REM) is an evaluation method that offers a way of responding to this challenge. REM is a participatory, qualitative method that brings stakeholders together to map the “ripples” of impact generated by an intervention5. Through structured workshops, participants use visual mapping to trace how activities lead to sequences of outcomes over time, capturing both intended and unintended impacts. In our experience, the output is not simply a list of impacts, but a visual and narrative account of how change contextually unfolds across a wider system. By mapping impacts as interconnected pathways, REM enables evaluators and stakeholders to see how relatively small actions can trigger wider effects in ways that could remain invisible through more conventional methods. Impacts that are typically difficult to evidence (such as strengthened relationships, increased confidence or new collaborations), become visible and meaningful when mapping the broader story of change6,7.
From data collection to shared learning
The process itself is central to its value, as REM workshops create a space for reflection, where stakeholders are encouraged to consider what has worked, what has been most significant (mechanisms), and what has emerged unexpectedly5. This reflective element deepens understanding of programme mechanisms, acceptability, and feasibility, and can directly inform ongoing adaptation. Rather than positioning evaluation as something done to programmes, REM embeds it within practice as a shared, learning-oriented activity. This participatory approach supports more inclusive evaluation, bringing stakeholders closer to the process and encouraging a learning partnership. By bringing together practitioners, community members, and partners, REM values different forms of knowledge and experience, often surfacing insights that are missed in more extractive approaches. For practitioners, this can be critical, as local context and lived experience are central to understanding what works, for whom, and under what circumstances.
Beyond evaluation: supporting adaptation and practice
Emerging evidence suggests that REM can extend beyond evaluation into practice3. In our experience, stakeholders have used REM outputs to inform their own work, supporting planning and decision-making in complex programmes. In some cases, practitioners have actively adopted REM as a tool within their own roles, suggesting that it can help bridge the gap between research and practice. It can be used iteratively, with follow-up sessions allowing stakeholders to revisit and extend the map as new developments emerge. This makes it particularly well-suited to initiatives that are adaptive, developmental, place-based, or operating across multiple sectors. By identifying chains of events and impact pathways, REM supports a more dynamic understanding of change over time, rather than a static snapshot5,7.
Challenges and considerations in using REM
However, REM is not without its challenges. The method requires skilled facilitation to ensure that sessions are inclusive and productive, and careful attention to group dynamics, particularly where power imbalances may shape whose voices are heard. In addition, practical constraints such as engaging a diverse range of stakeholders and coordinating sessions, can also limit the method’s success. While REM can generate rich and meaningful insights, our experience is that translating these into formats that align with commissioning or accountability requirements may require combining REM with other methods. These challenges are not unique to this method and reflect the broader difficulty of evaluating complex systems in ways that are both rigorous and meaningful.
Rethinking impact in complex systems
Perhaps the most important contribution of REM is that it encourages evaluators to rethink what we mean by impact. In complex systems, impact is rarely singular, attributable, or immediate. It is distributed across relationships, organisations, and systems, often emerging in ways that cannot be fully anticipated at the outset. REM provides a way of capturing this complexity without reducing it, offering a richer and more nuanced account of change. Ripple Effect Mapping is not a replacement for other approaches, but it is a valuable addition to the evaluator’s toolkit. By embracing complexity, encouraging participation, and making visible the often-unseen dimensions of change, it can help us to better understand the kinds of transformations that complex programmes are designed to achieve.
Our thanks to Oliver Hamer and Jade Thomson for this guest blog and for contributing their perspective to the UK Evaluation Society’s work.
References
- Norwitz ER, Rubin G, Reed-Tsochas F. Healthcare as a complex adaptive system: understanding health disparity as an emergent phenomenon. Curr Obstet Gynecol Rep. 2025;14:20. doi:10.1007/s13669-025-00425-1
- Systems theory in evaluation: understanding complex social systems. 2023 [cited 2026 Mar 19]. Available from: https://www.evalcommunity.com/career-center/systems-theory/
- Harris K, Nobles J, Ryan L, Szedlak C, Taylor H, Hawkins R, et al. Towards realist-informed ripple effects mapping (RREM): positioning the approach. BMC Med Res Methodol. 2024;24(1):259. doi:10.1186/s12874-024-02371-7
- Jabeen S. Unintended outcomes evaluation approach: a plausible way to evaluate unintended outcomes of social development programmes. Eval Program Plann. 2018;68:262–274. doi:10.1016/j.evalprogplan.2017.09.005
- Nobles J, Wheeler J, Dunleavy-Harris K, et al. Ripple effects mapping: capturing the wider impacts of systems change efforts in public health. BMC Med Res Methodol. 2022;22:72. doi:10.1186/s12874-022-01570-4
- Peterson C, Skolits G. Evaluating unintended program outcomes through ripple effects mapping (REM): application of REM using grounded theory. Eval Program Plann. 2019;76:101677. doi:10.1016/j.evalprogplan.2019.101677
- Washburn LT, Traywick L, Thornton L, Vincent J, Brown T. Using ripple effects mapping to evaluate a community-based health program: perspectives of program implementers. Health Promot Pract. 2020;21(4):601–610. doi:10.1177/1524839918804506
How to cite this article
Hamer, O. and Thomson, J. (2026) Ripples, not straight lines: Evaluating change in complex programmes and interventions. UK Evaluation Society blog. Available at: https://evaluation.org.uk/ripples-not-straight-lines-evaluating-change-in-complex-programmes-and-interventions/ (Accessed: [insert date]).
Dr Oliver Hamer
Oliver is a Postdoctoral Research Fellow within the Evaluation and Policy Analysis Unit (EPA Unit) at Edge Hill University. An experienced researcher, Oliver has six years of postdoctoral evaluation experience (PhD awarded in 2020), contributing to more than 20 evaluation projects across local authorities, the charity sector, the education sector, the NHS, and the NIHR (regionally, nationally, and internationally). He is currently a project manager on a range of health related evaluations, most notably the Welsh Ambulance Service Clinical Model Transformation programme evaluation and the BRITE programme evaluation.
Having spent time working for a local authority, Oliver is passionate about supporting public health practitioners to embed evaluation within programmes/ services to support learning and evidence impact. His experience across the public sector enables him to bring a real-world perspective to research and evaluation, offering practical and innovative approaches to evidencing impact, especially for those who face challenges with conventional methods. Read more.
Dr Jade Thomson
Dr Jade Thomson is a researcher at Edge Hill University, working within the Evaluation and Policy Analysis Unit. Her research focuses on programme evaluation, policy analysis, and qualitative research methodologies, with a particular interest in health and social care interventions. She is currently involved in the evaluation of two major projects:
- The Kentown Project – a three-year initiative aimed at improving nursing, respite, and social care for children with life-limiting conditions in Lancashire and South Cumbria. The evaluation examines both the process and impact of the programme, assessing its effectiveness in supporting families and service providers.
- The Barnardo’s Project – an evaluation of a Barnardo’s initiative, investigating its impact on vulnerable communities and assessing how its services can be adapted or expanded to meet long-term needs.
Her work supports organisations in refining their programmes, demonstrating impact, and shaping future policy. Read more.
