In project feasibility and early planning, what is the correct reason for preparing a conceptual (preliminary) cost estimate while drawings and specifications are still at an initial stage?

Introduction / Context:
Conceptual (preliminary) estimates are prepared early—often with limited scope definition—to guide go/no-go decisions, budgeting, and target setting. Even with sparse drawings, these estimates enable owners to size funding and compare alternatives, and they form a baseline for checking later quotes and definitive estimates as design progresses.

Given Data / Assumptions:

• Design definition is minimal (concept stage).
• Owner needs a target budget.
• Later, quotations and detailed estimates will be compared against this baseline.

Concept / Approach:

Conceptual estimates use parametric data, historical cost indices, and capacity or system-level metrics. They are less precise than definitive estimates but invaluable for early decisions, establishing targets, and sanity checking subsequent, more detailed numbers from bidders and the project team.

Step-by-Step Solution:

Verification / Alternative check:

Industry practice (stage-gate processes) always includes preliminary estimates before full design and tender documents exist.

Why Other Options Are Wrong:

• Any single reason understates the multi-purpose role of conceptual estimating.
• 'None of these' contradicts routine predesign budgeting practice.

Common Pitfalls:

• Treating conceptual estimates as definitive; they require contingency for scope growth.
• Not normalizing historical costs to current market conditions.

Final Answer:

All of these.