Research performance values are not certain. Performance indexes should therefore beaccompanied by uncertainty measures, to establish whether the performance of a unit istruly outstanding and not the result of random fluctuations. In this work we focus on theevaluation of research institutions on the basis of average individual performance, whereuncertainty is inversely related to the number of research staff. We utilize the funnel plot,a tool originally developed in meta-analysis, to measure and visualize the uncertainty inthe performance values of research institutions. As an illustrative example, we apply thefunnel plot to represent the uncertainty in the assessed research performance for Italianuniversities active in biochemistry.