Christian’s work has a profound impact on policy. He has co-developed the concept of the ‘Wellbeing-Year’ (or ‘WELLBY’ for short), a new measure of welfare in cost-benefit analyses which has officially been adopted by the UK and New Zealand Treasuries. It is now routinely used by governments for policy appraisal and evaluation, or by businesses and NGOs to demonstrate the social impact and value of their operations.
In A Handbook for Wellbeing Policy-Making (Frijters & Krekel, 2021, Oxford University Press), Christian has co-developed new methods for cost-benefit and cost-effectiveness analysis based on WELLBYs, which formed the basis for HM Treasury’s Green Book Supplementary Guidance on Wellbeing, the official guidelines for policy appraisal in the UK. He is a named advisor on these guidelines.
Christian was the Principal Investigator of the Value-for-Money project at LSE’s Centre for Economic Performance (CEP), which applied these new methods to major policies identified jointly with UK Government partners. This has led to Value for Money: The New Cost-Benefit Analysis Targeting Wellbeing (Frayman et al., 2026, Cambridge University Press), which formed the basis for an updated version of HM Treasury’s Green Book Supplementary Guidance on Wellbeing.
Christian is also the Principal Investigator and International Consortium Leader of ‘WELLMOD’, a project comprising 16 researchers from across LSE, Paris School of Economics, University of Luxembourg, and Polish Academy of Sciences. It aims at building the first wellbeing policy simulation model, which will allow analysts across all sectors (governments, businesses, and NGOs) to appraise any policy or intervention in terms of how much wellbeing it generates per unit of cost. The project is supported by the European Commission’s EUROMOD team and financed by a competitive grant from the European Union.
More recently, Christian has co-developed another method – experiential valuation based on people’s momentary feelings of happiness in real-time – as an alternative way to measure welfare. Together with George MacKerron of Sussex University, he applied it for the first time to estimate the monetary value of time (VOT) in 42 daily activities. The method provides a uniform way to measure welfare, allowing analysts to calculate monetary values of time and place for all possible activities and locations, their interactions, and contexts in people’s lives, depending only on researchers’ and policy-makers’ interests and willingness to sample them.