What is a Responsibility Assignment Matrix (RAM)?
A responsibility assignment matrix maps work (rows) to people or roles (columns) so every piece of work has explicit ownership. RACI — Responsible, Accountable, Consulted, Informed — is the most famous RAM format, but it's one flavor, not the whole family.
The non-negotiable rule carried from RACI: exactly one Accountable per row. Two accountables means none; zero means the work is an orphan.
Worked example
On a stadium project, the RAM row for "obtain occupancy permit" shows: site manager Responsible, project director Accountable, fire consultant Consulted, operator Informed. When the permit slips, nobody spends a week debating whose problem it is — the matrix already answered.