Imagine you’ve just been told that you’ll be a member of the team responsible for the first manned mission to Mars.

Now imagine someone asks you how much the mission’s going to cost. The whole thing. There and back. By close of business on Thursday.

A whole product is often a complex combination of several products and services. Some you create yourself, some are created by others. You’re responsible for the whole lot, even if they’re not all directly in your control.