Protocol
Re-estimate when evidence changes, not when anxiety spikes
A forecast should move because the model changed.
When it fits
- A team repeatedly changes the date in response to pressure without new information.
When to avoid it
- Sometimes a commitment must change for business reasons even without new delivery evidence; label that as a commitment change, not a forecast discovery.
Why it matters
Define evidence triggers that justify revision: scope change, dependency delay, measured throughput, failed test, discovered rework or resolved uncertainty. Record the changed input and its effect on the range. Pressure can trigger a review, but it is not itself evidence.
Steps
- Every material forecast change points to a changed input, assumption or risk state.
An example
A failed data-quality check adds a reconciliation step, so the forecast moves; a manager asking twice does not.
Check your result
Every material forecast change points to a changed input, assumption or risk state.
Keep this limit in mind
- Sometimes a commitment must change for business reasons even without new delivery evidence; label that as a commitment change, not a forecast discovery.
Evidence and sources
Supports
IPA guidance notes that uncertainty and estimate range depend on the maturity and variability of input data, so estimates should evolve as design and evidence mature.
A later estimate can still be wrong; maturity narrows uncertainty only when real information has improved.
Cost Estimating Guidance · Estimate maturity and range