In my current project we are facing a challenge. I thought some of you if not all might have faced similar challenge. Infact I talked with many others in the BA community here around me and nobody had any concrete answers. Hence I thought might be interesting to know how you approach such a situation:

Current Challenge

The project team receives a BRD and gets a few weeks to request for project budget(end to end). They need a scientific approach / process to arrive to this number, which will give them the confidence that budget over runs do not occur for the project. Software development & testing costs are derived from FPA or other techniques/methodolgy based on inputs from RE. But there seems to be on technique (apart from experience and gut feelings)to estimate requirements engineering or am I missing something here ? (Do you already know of any such technique/methodology?)

Questions on the Situation:

1. In the initial study phase, what kind of deliverables apart from the high level estimates need to be provided (to back up the estimates).

2. How can we have the confidence that the estimates derived from this study do not vary more than 20% for the detailed estimate?

Does anybody have any views ? Or is aware of any techniques/Tools formulas to solve the above problems ?

Regards
Girish