Checklist
Put the slow external dependency on the forecast
The calendar belongs partly to whoever must answer next.
When it fits
- A plan estimates only work controlled by the team.
When to avoid it
- Do not turn dependency tracking into blame; the goal is to model the real system and improve it.
Checklist
- External dependencies named.
- Owner or provider named.
- Expected response window recorded.
- Fallback or escalation path exists.
- Dominant dependency visible in the delivery forecast.
Why it matters
Name approvals, vendor responses, environments, data deliveries and other dependencies that can block progress. For each, record owner, expected response window and fallback or escalation. If one dependency can dominate delivery, surface it in the headline forecast.
An example
A transport can be prepared today but production import depends on a change manager's approval window; the forecast states that dependency explicitly.
Check your result
A missed delivery can be decomposed into controlled work and dependency latency.
Keep this limit in mind
- Do not turn dependency tracking into blame; the goal is to model the real system and improve it.
Evidence and sources
IPA cost-estimating guidance recommends documenting assumptions and representing uncertainty with reasonably optimistic, most-likely and reasonably pessimistic positions where appropriate.
Three-point estimates are inputs to judgment or modelling, not proof of a probability distribution.
Cost Estimating Guidance · Estimate ranges and assumptions
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