Hi! Welcome to my page!

I’m Kien, a Research Fellow at the Centre for Care, ESRC Research Centre. My work spans applied data science, health economics, and climate and environmental economics, with a focus on institutional analysis and policy evaluation.

Methodologically, I work with causal inference (DiD/event study/RCT), econometrics, machine learning, large language models, including text-as-data applications, topic modeling, and forecasting for policy and risk analysis.

Open to research collaborations Download my CV

Research Interests

  • Health Economics
  • Sociology and Social Policy
  • Environmental Economics
  • Financial Economics
  • Applied Data Science
  • Monetary Policy

Education

  • PhD in Economics (University of Birmingham)

    Oct 2021 – Dec 2025

  • MA in Economic Development (Erasmus University Rotterdam)

    Oct 2013 – Oct 2015

  • Postgraduate certificate (Monash University)

    Jan 2021 - Jul 2021

Working
Papers

Improving Staff Retention at the RBFT – Econometric Data Analytics, Probabilistic Forecasting and Management Intelligence

Status: Ongoing project

Abstract

In this project, we develop and evaluate forecasting models to predict the probability of staff leaving the Royal Berkshire NHS Foundation Trust (RBFT) over horizons ranging from one to twelve months. We begin with conventional predictive models to identify key determinants of staff turnover and progressively implement advanced machine-learning approaches to enhance predictive performance. The final Balanced Random Forest models perform strongly across all forecasting horizons. At the 12-month horizon, the model achieves approximately 99.7% overall accuracy, recall close to 100%, and precision of around 96%, correctly identifying nearly all future leavers while maintaining a low false-positive rate. Performance remains similarly robust at the 6-month horizon, with precision around 90% and recall close to 100%. In line with management priorities, we also implement forecasting under a two-month notice-period setting, reflecting typical RBFT practice. Under this configuration, the model attains approximately 99.6% accuracy and around 94% precision, correctly flagging more than 99% of staff who subsequently leave. Cross-validation and expanding-window testing confirm that model performance remains stable and robust over time. The resulting framework functions as a practical early-warning system for staff retention. By identifying at-risk employees in advance, managers can intervene earlier, target support effectively, and reduce recruitment and training costs.

Co-authors: Shixuan Wang; Rita Fontinha

Words to the Wise: Do Green Bonds and Language Make an Impact on Greenness?

Status: Empirical work complete

Abstract

We examine whether corporate green bond issuance causally reduces firms’ greenhouse gas (GHG) emissions intensity and whether linguistic structure shapes this environmental impact. Using an unbalanced panel of 3,867 publicly listed non-financial firms across 65 countries (2010–2024), we implement a staggered Difference-in-Differences design, complemented by entropy balancing to strengthen comparability between treated and control firms. We find that green bond issuance leads to economically meaningful emission reductions of approximately 19–21% on average. The effects are stronger in carbon-intensive industries, among high-investment firms, and for long-maturity bonds, suggesting real operational adjustments rather than symbolic commitments. Crucially, we document a novel moderation channel: firms headquartered in countries with weak Future Time Reference (FTR) languages experience significantly larger emission reductions following issuance. This linguistic effect remains robust when using a CEO-level Weak-FTR index constructed via machine-learning-based phonetic classification. Our findings demonstrate that financial instruments and cultural-linguistic structures jointly shape corporate environmental outcomes.

Co-authors: Alessandra Guariglia

When Birds of Different Feathers Flock Together: Ethnic Diversity and Armed Conflict

Status: Empirical work complete · Target: Personality and Social Psychology Bulletin (CABS 4)

Abstract

Ethnic diversity is frequently debated as either a structural source of instability or a foundation for long-term social resilience. However, existing research largely relies on static correlations and provides limited insight into how sudden increases in diversity affect conflict dynamics over time. Using panel data for 152 countries from 1990–2013, we conceptualize entry into the top quintile of the Historical Index of Ethnic Fractionalization (HIEF) as an exogenous diversity “shock” and estimate its dynamic effects on intra-state armed conflict. We find clear causal evidence that diversity shocks increase conflict intensity. Following a shock, conflict dyads rise significantly and remain elevated for approximately six years before gradually attenuating. This dynamic escalation–adaptation pattern constitutes a novel contribution to the literature, which has not previously clarified the temporal adjustment process following large shifts in ethnic composition. Mechanism analyses reveal substantial heterogeneity across regions and development levels. The effect is most pronounced in Asia and the Middle East, moderate in the Americas and Europe, and weaker elsewhere. Countries with lower Human Development Index (HDI) levels experience stronger post-shock conflict escalation, while higher-HDI societies demonstrate faster stabilization. Diversity shocks are also associated with higher conflict-related mortality rates, indicating effects not only on incidence but also on intensity. Our findings remain robust across two-way fixed-effects models, staggered difference-in-differences event studies, regression discontinuity designs around the diversity threshold, and alternative panel specifications. By isolating the dynamic shock component of ethnic diversity, our study clarifies when and where diversity destabilizes societies and how institutional capacity shapes subsequent adaptation.

Co-authors: Miguel R. Ramos; Matt Bennett; Unaysah Mogra

Funded
Research
Projects

  • Care Data Spaces – Adult Social Care Data Infrastructure, Centre for Care IMPACT Demonstrator scheme · WM-ADASS — Development of a regional data space and analytics platform across 14 West Midlands Local Authorities to support evidence-based policy and social care market analysis. Funding: ~£28,076 (2026-present)
  • HIP Collaborative Innovation Fund , Royal Berkshire NHS Foundation Trust - Forecasting NHS staff retention using machine learning and large-scale workforce data. Funding: £22,165. (2024-2025)
  • British Academy Funding , University of Birmingham — Analysing the labour market consequences of dengue outbreaks using Brazilian administrative data (RAIS and SINAN). Funding: £5,000. (2023)
  • National Foundation for Science and Technology Development (NAFOSTED) — Research on financial development, microfinance, and innovation among SMEs in Southeast Asia. Funding: £5,000. (2016-2017)

Grants
and Awards

  • Departmental PhD Scholarship, University of Birmingham (2021) — awarded +3 years of support.
  • Development funds, University of Birmingham — supported advanced study at Oxford, Michigan State University, and LSE.
  • Certificate of Distinction, University of Western Australia.
  • Research Excellence Certificate, Vietnam Netherlands Program.
  • Best Master’s Thesis (Distinction), Erasmus University Rotterdam — awarded €300.
  • National Project (NAFOSTED), Ministry of Science and Technology, Vietnam — awarded £5,000.

Contact

  • k.s.nguyen@bham.ac.uk
  • The Centre for Care, ESRC Research Centre (Sheffield · Birmingham · Oxford · LSHTM · ONS)