Given a business case with even a modest 20-30 variables/dimensions on which one would base the case, how does anyone going over it decide whether it is 'worth it'?
I mean if looking at a business case in isolation, what is it the 'human mind' looks at to make this decision? Is it that multiple business cases are required to be in the same format/variables/dimensions for easy comparison and they are rank ordered in the heads of the reviewers or is there more rigor to it?
Is each variable/dimension also 'rank ordered' to gauge its relative importance to the others - this is valuable when comparing multiple cases so you know which one seems better, but for a 'single' business case doesn't seem to be all that worthwhile.
Does the reviewer simply just look at ROI in the end and be content (or not) with that and the other variables just exist to justify that ROI?
I basically want to know how is it done, in your opinion and how much of it is rigor vs. gut-feel/intuition/experience...