A named assumption, dependency, novelty or information gap that could materially change a forecast and can be linked to a learning action or decision.

# Uncertainty driver

This is an editorial synthesis grounded in the source's underlying uncertainty discipline, not a term defined by GAO. Naming the driver is intended to show what evidence could narrow the range and where a decision-maker may need to alter scope, sequence, funding or risk appetite.

An uncertainty driver is not automatically a risk event. Some variation is inherent even when no discrete event occurs.

## Sources

- gao-cost-estimating-guide-2020 (primary)