Validation Begins With a Bounded Intended Use
A dosing service may produce a numerically correct recommendation and still be unsuitable for clinical deployment. The recommendation might be shown in the wrong workflow, be misunderstood by an intended user, or behave unsafely when required information is unavailable. A validation plan makes these concerns testable before release by connecting the service’s intended use to the components, users, settings, tests, criteria, and evidence that matter for that use.
The scope must be specific enough to determine what is in and out. State the clinical purpose, patient population, medication and dosing decisions covered, intended users, care settings, and conditions under which the service should not be used. Bound the software version and relevant configuration as well. A change in any of these boundaries can invalidate some or all of the evidence; a plan is not a general certificate that a product is safe in every context.
Validation here concerns the deployed clinical service as a whole, not just a model’s predictive performance. The matrix can include the model, application logic, workflow behavior, user-facing recommendation, operational safeguards, and relevant configuration. It should assign clear boundaries to each test. Detailed verification of data pipelines and interface outputs, analytical evaluation of predictions, and cross-site or temporal validation require their own specific methods; the matrix should identify where those activities belong without treating a general checklist as a substitute for them.
Constructing the Matrix
Start with requirements that describe observable behavior or a clinical constraint. “The service should be safe” is too broad to test. “For a patient with a required input missing, the service must not present a new dose as ready to act on” is more testable. Requirements may come from intended-use boundaries, clinical workflow needs, known hazards, and performance requirements. Each requirement should have a stable identifier so that a test result can be traced back to it.
For each requirement, name the relevant software components and configurations, the users who need to perform or interpret the task, and the settings in which the behavior must hold. A test that covers one clinician role in one configuration does not automatically establish the same behavior for a different role or setting. Specify test methods before execution: for example, scenario-based testing, inspection of controlled records, simulation of a defined operating condition, or structured assessment with intended users. State the acceptance criterion before seeing the result.
The following columns make those links explicit. Add fields such as owner, planned date, status, defect reference, or release impact if they help manage execution, but do not let administrative fields replace the testable links.
| Matrix field | Question it answers | Useful content |
|---|---|---|
| Requirement or risk control | What must be true? | Unique ID, observable behavior, source, and risk addressed |
| Intended use and boundary | For whom and under what conditions? | Population, medication, decision, exclusions, and operating condition |
| Component and configuration | What part of the service is implicated? | Named component, release, relevant configuration, or dependency |
| User and setting | Who must use or interpret it, and where? | Role, care setting, workflow context, and necessary coverage |
| Test method and test case | How will the requirement be evaluated? | Procedure, scenario, expected observation, and responsible tester |
| Acceptance criterion | What result counts as passing? | Threshold, permitted exceptions, and failure rule stated in advance |
| Evidence and disposition | What supports the decision? | Versioned protocol, results, deviations, defects, review, and approval |
Traceability should work in both directions. Starting from a requirement, a reviewer should find its tests and results. Starting from a test, a reviewer should find the requirement or risk it addresses. Requirements with no test are potential coverage gaps; tests with no rationale may consume effort without supporting a release decision. Retained evidence should identify what was tested, with which version and configuration, by whom, when, what happened, and how deviations or failures were resolved.
Worked Example: Turning a Clinical Constraint Into a Test Row
Consider a hypothetical inpatient service that provides a maintenance-dose recommendation for a specified medicine in adults. One requirement is that a recommendation must not appear ready for action when a required clinical input is missing. The plan applies only to the stated adult inpatient use and a named release.
A traceable row could be: Requirement R-04: with the required input absent, the service does not present a new dose as ready to act on. Component: the recommendation service and its presentation in the defined workflow. User and setting: the prescribing clinician in the inpatient workflow. Method: execute a controlled scenario in which the required input is absent, then inspect the state presented to the user. Criterion: in all 10 pre-specified repetitions, no new dose is presented as ready to act on, and the missing-input condition is apparent. Evidence: the approved protocol, release and configuration identifiers, ten recorded outcomes, any deviations, and an independent reviewer’s disposition.
The arithmetic is simple but clarifies the criterion: \(10/10=1.00\), or 100% of repetitions must meet both stated conditions. A result of 9/10 fails this criterion; it is not rounded into a pass. This test supports this one requirement under the defined scenario. It does not establish that every input is handled correctly or that the service is fit for all populations and settings.
Risk, Coverage, and Acceptance Criteria
A plan is more useful when test effort reflects the consequences of failure. A practical approach is to identify hazards and controls, then prioritize requirements by the potential clinical severity of failure, the likelihood of the relevant condition, and the chance that the failure will go undetected before affecting care. A simple qualitative scale can help organize discussion, but a single numerical risk score should not be treated as an objective measure of safety. Document the rationale for high-priority tests and for any requirement receiving less intensive coverage.
Coverage must be defined by the required combinations, not by the number of tests alone. If a behavior is required across two user roles and two settings, the plan must identify which of the four role-setting combinations need evidence. If some combinations are genuinely out of scope, record that boundary and its rationale rather than silently excluding them. A high overall pass percentage can conceal a missing test of a high-risk combination.
Acceptance criteria should be precise enough that two reviewers can classify the same result consistently. Avoid criteria such as “works as expected,” “acceptable usability,” or “no major issues” unless the plan defines how those judgments will be made. A criterion can be quantitative, such as a maximum response time under a defined condition, or qualitative but structured, such as a specified task being completed without a critical use error under a stated protocol. State whether any exception is permitted and how it will be handled.
There is a short reason to keep requirements, tests, and criteria linked. Let \(R\) be the set of requirements in scope, and let \(T(r)\) be the set of planned tests linked to requirement \(r\). If some \(r\in R\) has \(T(r)=\varnothing\), then no test result can support a conclusion about that requirement. Even if every other test passes, the plan has an evidence gap. Conversely, a test result only supports a conclusion when its method actually exercises the stated condition and its criterion was set in advance. Thus completeness of the matrix is a necessary condition for a defensible release decision, though it is not by itself proof of clinical fitness.
Worked Example: Checking User-and-Setting Coverage
Suppose a hypothetical service is intended for two user roles, physicians and pharmacists, in two settings, a general ward and an intensive care unit. The plan marks all four role-setting combinations as required for one workflow requirement. Three combinations have completed test evidence and met the criterion; the physician–intensive-care combination has no result.
The simple completion fraction is:
This is a status summary, not a pass rate for clinical safety. Because all four combinations were designated required, the requirement is not fully covered, even though the three completed combinations passed. The appropriate disposition is to complete the missing test, or to revise the intended-use boundary through an approved decision before release. It would be misleading to report “100% passed” by calculating only among completed tests without also reporting the missing required combination.
Execution, Failure Modes, and Release Decisions
Before execution, review whether each test is reproducible: are the starting conditions, version, user role, setting, expected observations, and pass rule clear? During execution, record actual outcomes rather than only a pass/fail label. Deviations matter because they may mean a test did not evaluate the intended condition. A failed test should be linked to a defect or documented rationale, assigned a disposition, and retested when a correction is made. Retest the affected requirement and consider whether the change affects related components or previously completed evidence.
Use a release rule that is consistent with the risk plan. One defensible rule is that every high-risk requirement and every requirement marked as mandatory for the intended use must have complete, passing evidence, with no unresolved failure that could compromise that use. Lower-risk findings may still need resolution or documented acceptance by an authorized decision-maker. “Most tests passed” is not an adequate rule when one untested or failed case concerns a severe hazard.
Operational monitoring is complementary rather than a substitute for pre-deployment validation. The earlier material on Operational Monitoring for a Live Dosing Service concerns observing performance after the service is live; a validation plan establishes the evidence and decision criteria required before release. Monitoring cannot make an inadequately tested release safe after the fact.
Worked Example: Applying a Predefined Release Rule
A hypothetical validation plan contains 24 required tests: 8 high-risk and 16 standard-priority tests. The release rule states that all high-risk tests must pass, at least 15 of the 16 standard-priority tests must pass, and no unresolved failure may affect a mandatory safety requirement. Results show 8/8 high-risk tests passing and 15/16 standard-priority tests passing. The remaining standard-priority test fails, but its requirement is confirmed not to be mandatory or linked to a high-risk control; an authorized reviewer documents the limitation and disposition.
The standard-priority pass fraction is \(15/16=0.9375\), or 93.75%. The plan’s numerical threshold is met, and the high-risk condition is met. Under the stated rule, the test results support release consideration, provided the failure’s documented disposition is accepted and all other required evidence is complete. If the failed test had instead concerned a mandatory safety requirement, the release rule would not be met despite the same overall pass fraction. The decision follows the predefined rule, not an after-the-fact interpretation of the percentage.
Common warning signs include vague intended-use boundaries, missing user-setting combinations, tests with no linked requirement, criteria written after results are observed, and evidence that cannot be tied to a release configuration. Another pitfall is treating a completed checklist as proof of validity. A matrix organizes a case for deployment; weak requirements, unrealistic scenarios, or inadequate methods can still produce a complete-looking but uninformative plan.
A validation matrix is also not a replacement for every technical evaluation. It should identify the needed work and its ownership while preserving the boundaries between whole-service validation and specialized assessments. Its main value is disciplined traceability: reviewers can see what the service is intended to do, which risks and users were considered, what evidence was obtained, and why the deployment decision follows from that evidence.
Check Your Understanding
Answer each question using the principles of a bounded, traceable validation plan. Solutions follow the questions.
- A requirement says, “The recommendation should be clear.” Name two changes that would make it more testable.
- A requirement applies to three settings, all designated as required. Evidence exists for two, and both tests pass. Is the requirement fully covered? Explain.
- Why should acceptance criteria be set before test execution?
- A plan reports 98% of tests passing, but one unresolved failure concerns a mandatory safety requirement. Does the percentage establish that the release rule is met?
- What should a reviewer be able to trace from a test result, and why is a result without a linked requirement potentially unhelpful?
Solutions. (1) Specify an observable outcome and a method or criterion—for example, define the task the intended user must complete and how completion or a critical error will be recorded. (2) No. One required setting lacks evidence, so coverage is incomplete even though the tested settings passed. (3) Predetermined criteria reduce the risk of changing the pass rule to fit observed results and let reviewers classify outcomes consistently. (4) No. The mandatory safety failure violates the stated release condition; an aggregate percentage cannot override it. (5) The reviewer should trace the requirement, intended condition, version and configuration, method, actual result, criterion, deviations, and disposition. Without a linked requirement, it may be unclear what clinical need the test addresses or what conclusion its result supports.