Ethnic parity in labour market outcomes for benefit claimants

We use UK administrative data to estimate the differential in labour market outcomes between Ethnic Minority benefit claimants and otherwise identical Whites. In many cases, Minorities and Whites are simply too different for satisfactory estimates to be calculated and results are sensitive to the methodology used. This calls into question previous results based on simple regression techniques, which may hide the fact that observationally different ethnic groups are being compared by parametric extrapolation. For some groups, however, we could calculate satisfactory results. In these cases, large and significant raw penalties almost always disappear once we appropriately control for pre-inflow characteristics.Ethnic, employment, benefit, discrimination, matching

Modelling Socio-Technical Transition Patterns and Pathways

We report on research that is developing a simulation model for assessing systemic innovations, or 'transitions', of societal systems towards a more sustainable development. Our overall aim is to outline design principles for models that can offer new insights into tackling persistent problems in large-scale systems, such as the European road transport system or the regional management of water resources. The systemic nature of these problems is associated with them being complex, uncertain and cutting across a number of sectors, and indicates a need for radical technological and behavioural solutions that address changes at the systems level rather than offering incremental changes within sub-systems. Model design is inspired by recent research into transitions, an emerging paradigm which provides a framework for tackling persistent problems. We use concepts from the literature on transitions to develop a prototype of a generic 'transition model'. Our prototype aims to capture different types of transition pathways, using historical examples such as the transition from horse-drawn carriages to cars or that from sailing ships to steam ships. The model combines agent-based modelling techniques and system dynamics, and includes interactions of individual agents and sub-systems, as well as cumulative effects on system structures. We show success in simulating different historical transition pathways by adapting the model's parameters and rules for each example. Finally, we discuss the improvements necessary for systematically exploring and detailing transition pathways in empirical case-study applications to current and future transitions such as the transition to a sustainable transport system in Europe.Complex Systems, Agent-Based Modelling, Social Simulation, Transitions, Transition Theory

On Implicit Bias in Overparameterized Bilevel Optimization

Many problems in machine learning involve bilevel optimization (BLO), including hyperparameter optimization, meta-learning, and dataset distillation. Bilevel problems consist of two nested sub-problems, called the outer and inner problems, respectively. In practice, often at least one of these sub-problems is overparameterized. In this case, there are many ways to choose among optima that achieve equivalent objective values. Inspired by recent studies of the implicit bias induced by optimization algorithms in single-level optimization, we investigate the implicit bias of gradient-based algorithms for bilevel optimization. We delineate two standard BLO methods -- cold-start and warm-start -- and show that the converged solution or long-run behavior depends to a large degree on these and other algorithmic choices, such as the hypergradient approximation. We also show that the inner solutions obtained by warm-start BLO can encode a surprising amount of information about the outer objective, even when the outer parameters are low-dimensional. We believe that implicit bias deserves as central a role in the study of bilevel optimization as it has attained in the study of single-level neural net optimization.Comment: ICML 202

Welsh language transmission and use in families: [final report]

The project aimed to examine how parents use Welsh with their children and how the use of Welsh in the home is influenced by various factors. Specifically, the project aimed to answer the following research questions: What are the conditions that facilitate Welsh language transmission within families, and the conditions that make Welsh language transmission less likely? What are the conditions that influence patterns of Welsh language use within families with children in the 0-4 age group? The research report includes: a thorough literature review of work on intergenerational language transmission internationally and previous research on the intergenerational transmission of Welsh; a statistical analysis of data relevant to the transmission of Welsh from the National Census (2011); a mixed-method (quantitative and qualitative) analysis of original data collected from 60 families through written questionnaires and semi-structured interviews; a thorough discussion of quantitative and qualitative findings and recommendations for further research and for policy for Welsh Government and partners