noun: clearness or lucidity as to perception or understanding; freedom from indistinctness or ambiguity.
When performing a BI project, everybody must be clear in their understanding of what is going to be delivered, why, when, how, and at what cost. Ambiguities in the project's mission, tactical approach, or deliverables will lead to failure.
I have recently used a low-fidelity wireframe tool from a software vendor named Balsamiq to reduce ambiguity. This mockup tool helps to quickly define the BI initiative in a collaborative approach.
Not only can business users see an example of what is going to be built, they can interact with it. The Balsamiq Mockup application has simulated links for demonstrating button clicks, listbox pull-downs, drill-downs, and other common user interface controls.
Before any real application development starts, the users can test out your plans and bless the user interface design. Issues can be pointed out immediately, not after weeks or months of costly effort.
Mockups force everybody to put ideas into a quasi-working format and validate feasibility.
I am a fan of Balsamiq Mockups. At $79 USD, it is a cheap way to bring clarity to your BI project.