Definition of Authority Matrix
An authority matrix is a list or table that sets out who can approve a change, subject to cost limits, or areas of responsibility.
For example, the manager or company representative for a particular work site may be able to approve changes up to a certain limit, that only have an effect on the work at that site, but would not be able to approve changes above that limit, or that might affect multiple sites.
The project manager should be able to approve most changes that are inside the scope framework of the project, but will probably NOT be able to approve changes that would need to make use of the management reserve.
The authority matrix is used to choose the people that will review, recommend and approve (or not) a change.
Some or all of these people may attend the Change Board.