Implementing New Methods

This guide is for contributors adding or extending the stable core VOI methods in voiage.

Current stable method surface

• evpi
• evppi
• evsi
• enbs
• calculate_ceaf
• calculate_dominance
• value_of_heterogeneity

Before you start

Review existing implementations before adding a new method:

• voiage/methods/basic.py for EVPI and EVPPI
• voiage/methods/sample_information.py for EVSI and ENBS
• voiage/methods/ceaf.py for CEAF summaries
• voiage/methods/dominance.py for dominance and frontier calculations
• voiage/methods/heterogeneity.py for subgroup-aware value calculations

Method shape

Keep function signatures explicit, typed, and easy to route from the analysis facade. Accept structured inputs rather than raw arrays where possible, return a dataclass or result object for multi-field summaries, and keep the public wrapper on DecisionAnalysis thin.

Implementation checklist

1. Add the method implementation under voiage/methods/
2. Use existing schema objects or add a new one in voiage/schema.py
3. Add a DecisionAnalysis wrapper if the method belongs on the main analysis surface
4. Export the new method from voiage/methods/__init__.py
5. Add unit tests covering normal inputs, boundary conditions, and validation failures
6. Add or update user-guide examples
7. If CLI-visible, add the command or option wiring and test it
8. Update the changelog and todo tracking entry