Every objective has certain elements that are fundamental to its success. These include the supporting tasks or systems that we take for granted but without which our “real” work could not get done. In order for any organization or team to meet its primary objectives, these fundamentals need to be functioning properly.

Research suggests that humans are biased, not-very-rational decision-makers. We believe we see things clearly when the evidence shows otherwise. Throw in a big dose of optimism, and it's easy to see how estimating software projects can be problematic. Our best hope is to construct diverse groups with varied viewpoints.

There's a simple rule for the minimum values testers should explore: “none, one, some”—or, how the software behaves if you send it nothing, one thing, or some set greater than one. It's not comprehensive, but it gives a good feel for how the feature works at the moment. Developers can also use this in unit testing.