In his "Undercover Economist" column (August 12, 2026), Tim Harford discussed a new working paper by John List, Matthias Rodemeier, Sutanuka Roy, and Gregory Sun, which reviews more than 600 studies of behaviourally informed public policies to ask how significant "nudges" really are. The paper quantifies the impact of nudge-style interventions by comparing them to the equivalent price change required to achieve the same effect -- finding, for example, that matching the best behavioural interventions would require substantial tax increases. At the same time, the authors show that traditional instruments such as taxes and subsidies deliver the largest total welfare gains: the optimal energy tax generates roughly seven times the total welfare of the optimal nudge, even though the nudge is more cost-effective.

Matthias's research lies at the intersection of behavioral economics and public finance, with a focus on environmental policy and consumer finance. Many of his studies use field experiments conducted in collaboration with private and public organizations.