# Improving the Comprehension of Risk Matrices by the Public

In order to prioritize resources and make decisions when mitigating or preparing for hazards, risk managers and responders need to understand those hazards’ likelihoods and potential impacts. A common way to represent these is via a risk matrix: a table or graph illustrating likelihood on one axis and potential impact on the other. Hazards are then graphically represented by being located in the appropriate section of the matrix space. This allows an ‘at-a-glance’ assessment of the risk a given hazard poses and of the potential effects of mitigation measures, and a comparison between it and other hazards in the matrix.

However, despite the widespread useage of risk matrices, there is little information on how well people understood risk information when represented on them. I ran a randomized controlled trial to understand how several different designs of risk matrix, ways of labelling the axes, and formats of presenting probability information affected people’s ability to understand and evaluate risk information. A new design of risk matrix that I developed performed better than a standard risk matrix or text-based risk information. My improved design was used by the Cabinet Office in the 2020 UK National Risk Register.

As part of this role, I also worked on some other projects. I conducted a systematic literature review on communicating strength of evidence to the public; took part in public engagement activities; and assissted with several replication projects.

My work on this project was continued after I left for my PhD, and there is a follow-up paper on how the use of colour in risk matrices can influence risk comprehension: Proto, R., Recchia, G., Dryhurst, S., Freeman, Alexandra L. J. (2023) Do colored cells in risk matrices affect decision-making and risk perception? Insights from randomized controlled studies. Risk Analysis. https://doi.org/10.1111/risa.14091

*At the University of Cambridge, October 2019 to September 2020. Funded by a philanthropic donation from the David and Claudia Harding Foundation.*