Donald Rumsfeld is famous (to me) for talking about the known knowns [1]. It was in 2002 where he talked about the absence of evidence on mass destruction weapons in Iraq. Add to that the angle of the unknown known, and I can call it the “Rumsfeld Rectangle“.

You could apply it in test strategy setting like this:

Rumsfeld Rectangle:

What do the stakeholders want from this test activity?

What do they Know

they want to Know

What do they Don’t Know

they want to Know

What do they Know

they Don’t want to Know

What do they Don’t Know

they Don’t want to Know

I have used the Rumsfeld Rectangle previously in The unknown unknown unexpressed expectations and How to spot defects. The tricky problems are (as always) in the areas of “there are things we do not know we don’t know” spot – as for Rumsfeld. Combing the desert showed the absence, not the presence of weapons (to rephrase Dijkstra [2]).

I – equally ignorant – do not believe [that I know anything] [3]

1: [ There are known knowns United States Secretary of Defense, Donald Rumsfeld |

[T]here are known knowns; there are things we know that we know.There are known unknowns; that is to say there are things that, we now know we don’t know.But there are also unknown unknowns – there are things we do not know we don’t know.”

2: Dijkstra 1969: Testing shows the presence, not the absence of bugs

3: Piet Hein Seriously joking or joking seriously