Editorial

The winter 2023 issue of the International Journal of Microsimulation is published as the International Microsimulation Association heads to its 9^th World Congress (Vienna, Austria, 8^th - 10^th January 2024). The issue contains five articles, covering different microsimulation techniques and applications. The first article, by Karl Widerquist and Georg Arndt, is a static tax-benefit analysis of a Universal Basic Income (UBI) scheme for the United Kingdom (UK). The analysis reflects a growing interest in UBI worldwide, and adds to an active discussion of UBI schemes for the UK in particular (see Torry , 2023). The second article, by Montserrat Gonzalez Garibay, contains a review of how retirement decisions are modelled in dynamic microsimulation models (DMSs). The paper fills a gap in the literature, as existing reviews of DMSs (e.g. O’Donoghue, 2001; Li and O’Donoghue, 2013; O’Donoghue, 2014; O’Donoghue and Dekkers, 2018; Schofield et al., 2018) generally favour breadth of coverage to depth of modelling insights. The third article, by Edlira Narazani, Ugo Colombino and Bianey Palma, pushes forward the boundaries of tax-benefit modelling by adding both behavioural labour supply effects and endogenous wage adjustments to a static tax-benefit framework. Their model is estimated on all EU member states, but is unfortunately not available outside the European Commission. The fourth article, by Rachel Bacon, George Hodulik, David Voas, Ivan Puga-Gonzalez and Wesley Wildman, confronts with the problem of replicating official population projections in discrete-time DMSs where events like births, deaths, ageing, fertility and migration are simulated in turn - implying that the order of execution matters - while in reality the related risks are competing. The solution envisaged is to “split fertility”, attributing half of the risk at the beginning of the simulation period, and the remaining half at the end of the simulation period. The last article, by Tanja Kirn and Gijs Dekkers, is ideally linked to the review by Gonzalez Garibay, illustrating a new DMS for projecting pension entitlements in Switzerland. The model builds on the popular LIAM2/MIDAS simulation frameworks (de Menten et al., 2014; Dekkers et al., 2022) to analyse the likely impact of a recent pension reform on the gender pension gap.