The skills matrix (also called a competency or cross-training matrix) crosses people with the competences the processes require, showing on a single screen who is qualified for what — and where the dangerous gaps are. It is the structural evidence for clause 7.2 of ISO 9001, which requires determining the necessary competence, ensuring it on the basis of education, training and experience, and keeping evidence.
The most widely used proficiency scale has four levels: 0 — not trained; 1 — in training (works under supervision); 2 — qualified (works alone); 3 — multiplier (works, trains and assesses others). With that, the matrix reveals the two risks that stop production most often: the orphan competence (only one person at level 2 or above — vacation, sick leave or a resignation turns into a crisis) and the uncovered shift (the competence exists but is concentrated in one shift). The practical safety rule: at least two people at level 2 or above per critical competence, per shift.
To keep the matrix from becoming wall decoration: define the objective criterion for each level (level 2 in welding = passed practical test X with a conforming dimensional inspection — signed off by the defined assessor, not by the supervisor liking you); update it by event (effective training completed, assessment at the workstation, termination) and not from memory; and connect the gaps to the training needs analysis — every red cell in a critical competence is a line of the training plan with a deadline.
The example below is from the production area of a metalworking company. Look at the CNC press brake row: a critical gap that was identified, turned into a risk in the risk matrix and into an action in the training plan — the traceability auditors praise.