Estimate Requirements Document

What the requirements document is

If the basis of estimate (Lesson 14) is written after to describe what was done, the ERD is written before to specify what should be done. It's the estimate's terms of reference — the contract between whoever needs the estimate and whoever produces it.

ERD vs basis of estimate

These two documents bookend the estimate and are easy to mix up. The clean distinction:

What goes into an ERD

A requirements document typically specifies:

1. Purpose & decision — why the estimate is needed and what decision it must support (gate, funding, bid).
2. Required class & accuracy — the target estimate class and expected accuracy, set by the decision's stakes.
3. Scope basis & documents — what's to be estimated and which design documents/data define it.
4. Deliverables & format — what outputs are required and in what structure (WBS, breakdown, currency).
5. Schedule & resources — when the estimate is due and what people, data, and budget are available to produce it.
6. Assumptions & constraints — known givens, ground rules, and any constraints the estimate must observe.

Using the ERD well

Treat the ERD as the agreed starting point for every significant estimate: draft it with the requester, confirm the class fits the decision, list the documents and resources the estimator will rely on, and get sign-off before work begins. It costs a little discipline up front and saves enormous rework — and it gives the estimator a fair standard to be judged against.

Nine things to remember

1. The ERD defines the requirements for an estimate before it's prepared.
2. It's the estimate's brief / terms of reference — agreed up front.
3. ERD is before ("what do we need?"); BOE is after ("how was it built?").
4. Begin with the end in mind — prevents producing the wrong estimate.
5. Specify purpose, class, scope, deliverables, schedule, assumptions.
6. The required class must match the decision — the ERD makes that match deliberate.
7. The BOE responds to the ERD — together they form a traceable loop.
8. Get sign-off before work begins — and judge the estimate against it.
9. Good estimates are well-commissioned, well-planned, and well-documented.