I was about to write that a guide to estimating savings or income from partial information would be really useful, then it occurred to me that, since businesses

I was about to write that a guide to estimating savings or income from partial information would be really useful, then it occurred to me that, since businesses & management do that a lot, this is probably exhaustively covered in business & management literature. Maybe some case studies of how to do this specifically with the kinds of info a software consultant (or, indeed, a low-ranked development employee—all are advised to attach a dollar value to their work for later bragging/self-promotion purposes, after all) may readily access, then, would be enlightening.