This session provided a very useful opportunity to take stock of the current state of the evidence base and to consider where research into the impact of public involvement may wish to go next. The key issue for me arising out of the session was that, although recent reviews of the evidence base have highlighted some of the key impacts that public involvement can have on research processes and outcomes, we still lack the methodological tools to accurately measure or evaluate these impacts.

We considered the relative value of qualitative and quantitative approaches to the evaluation of impact; the importance of public involvement in the design and conduct of such work; and how the new Public involvement impact Assessment Framework (PiiAF) can play an important role in the planning of such assessments. We agreed that some impacts of public involvement will be easier to capture or evaluate than others, while what might be considered ‘subtle’ or ‘indirect’ impacts of public involvement, such as culture change within a research group or organisation, would be especially difficult to evaluate.

Although impacts of public involvement have been identified, we do not know how important specific impacts of involvement are for different stakeholders, such as the public, researchers, commissioners, funders, and journal editors. We discussed the value of undertaking further research to identify key impacts of public involvement from different stakeholder perspectives, in order to generate a ‘PPI impact minimum data set’, which could be used in the development of a standardised quantitative measure of PPI impact.