Who knew it could be this simple? But apparently, in 1987, Tom Gilb did. Cleaning out my files I came across a photocopy I made from an (I think) unpublished 1987 Gilb book manuscript. Check it out.
What could be more direct or concise? I might rewrite "political value" as "customer" or "market" value, but aside from that it's agile all the way down. Every software developer and project manager should keep this posted nearby, and refer to it frequently.