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Forecasting & decision support for public health supply chains

Learning, engagement, and research from the Data Lab for Social Good, Cardiff University, UK

Harsha Halgamuwe Hewage

2026/02/12



Outline

Overview of our projects

Project 01: Contraceptive demand forecasting

Project 02: Demand forecasting with lost sales

Project 03: Supply chain forecasting using DHIS2/CHAP

Project 04: Foundation/LLMs models for demand forecasting

Portfolio map: four connected projects


Projects timeline and progress

Blue colour bars indicate the timelines from project start to draft manuscript completion.


Project 01: Family planning demand forecasting


Problem

  • Stock decisions are risk-based, point forecasts are not enough

  • Real LMIS data are irregular and often short-history

  • Planners need a transparent adjustment mechanism to incorporate expert knowledge

What we built

  • Hybrid approach: Combine probabilistic forecast with expert point forecast

  • Benchmark a wide range of forecasting methods for contraceptive forecasting

Project 01: Family planning demand forecasting


Outputs

  • Facility-level probabilistic forecasts (quantiles & intervals)

  • Hybrid method that balances accuracy and computational requirements

  • Guidance on when to use which method family

  • A hands-on training on demand forecasting for contraceptives

Key message

  • Use stable baselines by default; escalate to richer models selectively

  • Treat bias adjustment as a governance issue (who can override, when, and why)

Project 02: Demand forecasting with lost sales


Problem

  • Observed consumption underestimates true need when shelves are empty

  • Stockouts create partial censoring

  • Interruptions/closures create full censoring

  • Biased data → biased forecasts → under-ordering cycles

What we built

  • Truncated Conformal Kalman Filter (TCKF), forecasting method that adapts under lost sales

  • Prediction intervals suitable for decision rules (e.g., order-up-to policies)

Project 02: Demand forecasting with lost sales


Outputs

  • TCKF method for lost sales (stockouts and interruptions).

  • Prediction intervals via conformal prediction.

  • Integrated forecast and inventory pipeline linking accuracy to ordering decisions.

  • Public health translation from stock outcomes to program impact.

Key message

  • Stock data often hides need, so we must estimate “true demand,” not just forecast observed consumption.

  • Evaluate methods by decision impact (availability/ public health), not forecast scores alone.

Project 3: DHIS2/CHAP deployment for supply chain forecasting


Problem

  • CHAP supports advanced probabilistic forecasting, mainly for morbidity use-cases

  • Supply chain forecasting is not routinely linked to inventory decisions in the same workflow

  • Facility-level planning needs low-burden tools that run unattended across many series

What we built

  • A model portability experiment inside the DHIS2/CHAP pipeline (cases → consumption)

  • A standard workflow that produces forecast objects (mean, quantiles, sample paths) and feeds an order-up-to inventory simulation

Project 3: DHIS2/CHAP deployment for supply chain forecasting


Outputs

  • Portability evidence across accuracy, uncertainty, runtime, and failure risk

  • A practical default set: Auto ARIMA / Auto ETS as stable, scalable baselines

  • A proposed end-to-end architecture and deployment steps

Key message

  • Reuse the platform at scale, but treat model choice as conditional (target structure and decision context).

  • Start with autonomous baselines; add complex models only where inputs and governance justify them.

Project 4: Foundation/LLM models for public healthcare demand forecasting


Problem

  • Foundational/ LLM models are trained on commercial-scale time series, but public health LMIS data are different

  • In LMIS we see intermittency, censoring, short histories, and data quality constraints

  • Their value for facility planning (zero-shot vs fine-tuned) is still unknown

What we built

  • A controlled benchmark of foundation/LLM models vs strong statistical baselines on public health demand series

  • A Model Portability Matrix to explain when/why transfer works across domains, data regimes, and decision contexts

Project 4: Foundation/LLM models for public healthcare demand forecasting


Outputs

  • A portability matrix covering: domain, data regime, model complexity and computational requirements

  • Zero-shot vs fine-tuned results for models such as TimeGPT, Chronos, LagLlama, Moirai, TimesFM, etc

  • Practical guidance: “where foundation models help, where they don’t, and what to run instead

Key message

  • Treat foundation/LLM models as candidates, not defaults: test portability under LMIS realities before deployment.

Any questions or thoughts? 💬