Independent Quantitative Consulting

Decision-grade modeling on real decision timelines.

Model Stewardship supports global health philanthropies, NGOs, and implementation partners with rapid, reproducible quantitative analysis — built for consequential decisions on real timelines.

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No Institutional Agenda

Engagements are selected to preserve independence. Analysis serves your decision, not a funder's prior position.

Lean & Fast

No committee overhead, no co-PI delays. Deliverables move on your decision timeline, not an academic calendar.

AI-Accelerated

Modern AI tooling compresses literature synthesis, code generation, and model iteration — without cutting corners on rigor or reproducibility.

Decision Workflow

Structured analysis for high-stakes decisions.

Step 1

Define Decision Context

Clarify the exact decision, constraints, and policy clock so analysis starts with deployment intent.

Step 2

Deploy Quantitative Analysis

Stand up focused modeling and evidence synthesis using reproducible workflows and explicit assumptions.

Step 3

Deliver Decision Output

Translate technical results into decision-grade guidance leadership can use immediately.

Capabilities

Specialized quantitative support for consequential decisions.

Respiratory pathogen signature heatmap

Evidence Synthesis and Validation

Integrate diverse evidence streams into clear, decision-ready synthesis with explicit uncertainty.

  • Model review and validation
  • Cross-model reconciliation
  • AI-assisted literature synthesis

Selected publication: Chemokine gene expression signature study (BMC Syst Biol, 2011) • View publication

South Africa TB incidence scenario comparison

Infectious Disease Modeling

Build and stress-test transmission models for policy, trial, and program decisions under real timelines.

  • Scenario analysis and forecasting
  • Clinical trial design support
  • AI-accelerated model prototyping

Selected publication: South Africa TB mine workers modeling study (BMC Med, 2018) • View publication

Nigeria TB hotspot prioritization map

Geospatial Targeting

Target interventions with spatial analytics that connect disease burden, coverage gaps, and operational feasibility.

  • Hotspot identification
  • Coverage optimization

Client Focus

Built for global health philanthropies, NGOs, and public-sector implementers.

Engagements are selected to preserve independence and avoid conflicts. The model is designed for teams that need technical depth with short decision timelines and direct accountability to outcomes.

Mission Proof

Selected engagements, structured by context and decision impact.

Context

M72 TB Vaccine Trial Support

Support for phase 3 trial design activities with Gates Medical Research Institute.

Analytical Approach

Epidemiological modeling for sample design tradeoffs and operational feasibility.

Decision Impact

Better-aligned trial strategy for consequential funding and execution decisions.

Context

COVID-19 Prioritization

Constrained vaccine supply and urgent sequencing decisions.

Analytical Approach

Rapid modeling support for CEPI-aligned prioritization scenarios.

Decision Impact

Clearer allocation pathways under real rollout constraints.

View an example publication

Context

National TB Program Optimization

Country-level strategy choices across South Africa, Pakistan, and Nigeria.

Analytical Approach

Transmission and geospatial analytics to compare intervention portfolios.

Decision Impact

Evidence-informed targeting and program design for higher impact.

View an example publication

Engagement Model

Lean collaboration with explicit deliverables and short decision windows.

Engagements are structured to avoid the overhead that slows large-institution modeling work — fixed scope, direct delivery, and accountable outcomes.

  • Project sprint: Defined scope and delivery window, typically 4 to 12 weeks.
  • Advisory retainer: Ongoing support for rapid-turn decisions and model governance.
  • Technical review: Independent review of work produced by partner teams.
COVID vaccine prioritization scenario output
Field presentation in Nigeria

About

About Stewart Chang, PhD

Infectious disease modeler and quantitative strategist with 13 years at the Institute for Disease Modeling in the Gates Foundation ecosystem.

Model Stewardship was founded to bring that same analytical depth to organizations that need faster turnaround, cleaner accountability, and modern AI-enabled methods — without the overhead of large-institution engagement.

The practice is built for mission-driven organizations that need rigorous technical support with clear scope, reproducible methods, and accountable delivery.

Published in Lancet Global Health, BMC Medicine, and PLOS Global Public Health.

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Book Intro Call

Start with a focused intake.

Share your decision context, timeline, and target outcome. I respond directly.