Survey of Step 5

Document all cost-influencing ground rules and assumptions.
Document the rationale and historical data that support the ground rules and assumptions.
Include input from the technical community when developing ground rules and assumptions.
Document risks associated with assumptions and trace to specific WBS elements.

The estimate documents all cost-influencing ground rules and assumptions

There are defined ground rules and assumptions and the rationale and historical data to support them are documented.
The ground rules and assumptions have been developed by estimators with input from the technical community.
Risks associated with assumptions have been identified and traced to specific WBS elements. For example, effects related to budget constraints, delayed program content, dependency on other agencies, and technology maturity have been identified.
Cost-influencing assumptions are used as inputs to the sensitivity and uncertainty analyses.

If management is not informed of cost estimating ground rules and assumptions, it will not fully understand the conditions on which the estimate was structured. The subsequent rejection of even a single assumption by management could invalidate many aspects of the cost estimate.
Overly optimistic assumptions may influence the cost estimate, leading to inaccurate estimates and budgets.
Without analyzing the effects of an invalid assumption on the cost and schedule of a program, cost estimators and management will not have a full understanding of the effects of changing ground rules and assumptions.
Unless assumptions are documented with their sources and supporting historical data, decision-makers will not understand the level of certainty around the assumption or the cost estimate.