CSD matrix

A CSD matrix is a sheet with three columns: Certainties, Suppositions and Doubts. The team writes down everything it believes about a project and places each statement by how sure it really is. The output is not a diagram to admire. It is a ranked list of what you do not yet know.

How to run it

Everyone writes statements on sticky notes alone and in silence, one idea per note, then the notes go on the wall and the group argues about where each belongs. The one rule worth enforcing: a certainty needs evidence you could show someone. “Customers find the checkout confusing” is a certainty only if there is a recording, a ticket count or a test result behind it. Otherwise it moves to Suppositions.

What each column turns into

Certainties go into the brief and stop being discussed. Suppositions become hypotheses, and they are the cheapest to test, often with a survey or a handful of interviews. Doubts become open research questions and feed straight into the research plan.

Common mistake

The Certainties column fills up with opinions held by the most senior person in the room. The useful moment in a CSD session is when a confident note slides one column to the right, because that is the first time the team admits it has been designing from a guess. Do the exercise before you pick methods, not after.