Create a context-of-use matrix that separates direct users from stakeholders and identifies the task and testable constraints.
Context of use is not a generic fictional persona. It is the relationship among a particular user, goal, tool, environment and constraints while a task is being completed. A receptionist may operate a booking system directly, while the person waiting for a notice is affected by the result and a manager owns the policy decision. Putting all three into one user box hides different needs. Begin with a task to study: confirm a reservation, correct details or recover an application number. Specify its entry point, completion criterion and resources available to the person. Record conditions that could change performance, such as a shared device, intermittent connection, interface language, keyboard use or help from another person. Do not attribute such conditions to a whole group without observation; treat them as recruitment hypotheses or questions to verify.
A useful matrix has a row for each materially different task, rather than a row for every job title. Its columns can be goal, decision step, channel, environment, dependency on another actor, known evidence and evidence gap. Write 'the participant needed a booking number before leaving' if a session showed it, but write 'a printable copy may be needed' if that remains unobserved. Ask whether the task changes with a lost connection or a language switch. If it does, a single successful path cannot represent the whole context. Recruit for the usage patterns relevant to the decision, not merely the people easiest to contact. A manager interview can reveal operating rules but usually cannot replace observing a customer's behavior. End the map with a small research decision: which actor and step to observe next, and what finding would change the design?
Lesson summary
A useful matrix has a row for each materially different task, rather than a row for every job title.