This edition examines how randomised experiments can be used to inform economic policy in the Nordic countries. Drawing on experiences from large‑scale trials in areas such as taxation, labour markets, education, and social policy, the articles focus not only on what experiments reveal, but on how they are designed, authorised, and implemented in practice.
The volume discusses concrete challenges faced by policymakers, researchers, and public authorities, including legal and ethical constraints, institutional cooperation, take‑up, data access, and spillover effects, and shows how these can be addressed in real‑world settings. Together, the articles offer practical guidance on how experimentation can be integrated into policy design to support more robust, evidence‑informed economic policymaking in the Nordic Region.
The Norwegian Tax Experiment – From Idea to Implementation
Simen Markussen and Marie Bjørneby
In December 2025, 106,469 young Norwegians received their annual tax card (skattekort), which adds a new feature to the tax system in Norway: an earned income tax credit. The recipients are all part of a large real-world experiment, in which 8% of all taxpayers between the ages of 20 and 35 were randomly assigned to a treatment group. For this group, the tax system includes an additional earned income tax credit.
In this article, written before any results from the experiment have materialised, we present the experiment, how it came about, and how we worked on its implementation. We aim to present some of the challenges we encountered, as well as the insights we gained while working on the project.
Learning to Experiment: Practical Lessons from Finland’s Two-Year Preschool Experiment
Ramin Izadi and Matti Sarvimäki
This paper describes how Finland implemented a nationwide randomised field experiment to evaluate a potential reform of its early childhood education and care (ECEC) system. The two-year preschool experiment involved 37,357 children at 956 centres and was enabled by temporary legislation enacted specifically for this purpose. The trial was designed and executed in close collaboration between researchers, civil servants, and teachers, with two successive governments committing to wait for the results before making policy decisions. We document how the experiment was planned, legislated, and implemented, and analyse the institutional arrangements that made it possible. We highlight the value of sustained co-operation between policymakers and researchers, the benefits of a multidisciplinary research team, and how the experiment both relied on and reinforced Finland’s data infrastructure. We conclude by discussing lessons for other countries seeking to embed rigorous evaluation into their policy processes.
Evaluating Active Labour Market Policies Using Randomised Control Trials
Johan Vikström
This paper discusses randomised controlled trials (RCTs) of labour market policies in the Nordic countries. Evaluating labour market policies is essential to ensure that public resources are allocated to effective interventions that improve employment outcomes, yet credible evaluation is challenging because programme participation is often selective. RCTs address this challenge by creating comparable treatment and control groups and are therefore widely regarded as the gold standard in policy evaluation. Using illustrative examples, the paper illustrates key issues related to motivating, designing, implementing, and analysing RCTs in a labour-market policy context. The paper discusses ethical considerations, randomisation designs, implementation challenges, and analytical issues including take-up, outcome measurement, cost-effectiveness, and general equilibrium effects. It concludes that while the existing evidence base is substantial, continued experimentation and causal evidence remain important as labour market institutions and policies evolve.
Childhood and Adolescent Interventions in a Danish Setting: A Meta-Analysis of Evidence from TrygFonden’s Centre for Child Research
Stine Nyhus Larsen, Nikolaj Noer Poulsen, Michael Rosholm and Katrine Bønneland Tølbøll
This review and meta-analysis synthesises experimental and quasi-experimental intervention evaluations conducted at TrygFonden’s Centre for Child Research (TFCCR). The objectives of the paper were to estimate pooled effects on children’s learning and to explain between-study variation using cost-standardised effect sizes and coded information on intervention content, delivery and context, collected by means of a principal investigator survey. The eligible studies were RCTs or quasi-experiments that estimated causal effects on cognitive or educational outcomes, provided sufficient data to compute standardised and cost-standardised mean differences, and were conducted in Denmark by researchers affiliated with the Centre between 2013 and 2024.
Large-Scale Randomised Experiments with Population Data
Elias Einiö and Annika Nivala
This article features insights from the Finnish Recruitment Subsidy Experiment, which we designed and implemented along with the Ministry of Economic Affairs and Employment of Finland. It belongs to a class of randomised controlled trials characterised by large, national-scale, costly treatments and imperfect take-up, which are typical features of many public policies. The experimental setting is based on data drawn from population registers covering all individuals, firms or other relevant units of observation. Data of this sort are becoming increasingly common in many countries, and are particularly accessible in the Nordic Region. We address econometric issues typical for these types of settings, including the management of over- and under-subscription, as well as the calculation of statistical power with multiple experimental waves. We also discuss practical issues relevant to running large-scale national randomised experiments involving a research team and several parties from the public administration.
