Activity and Observation

Category: Governed definitions, occurrences, and observations
Review status: Proposed

Object chain

ActivityDefinition
  └── ActivityPlacement
      └── DomainActivityBinding
          └── ParticipantScheduleItem
              └── ActivityOccurrence
                  ├── Observation
                  ├── MaterialMovement
                  ├── Decision
                  └── EvidenceRecord

Activity Definition

Describes a protocol-level activity such as an assessment, procedure, specimen collection, contact, administration, or dispensation.

Field	Type	Meaning
identity	ActivityDefinitionIdentity	Stable identity within protocol intent
name	ActivityName	Human-readable clinical name
type	ActivityType	Governed activity classification
purpose	ActivityPurpose[]	Screening, efficacy, safety, treatment, follow-up, etc.
performerRequirement	PerformerRequirement?	Required qualification or responsibility
outputExpectations	ActivityOutputExpectation[]	Data, specimen, image, material, or evidence expected

Activity Placement

Defines one contextual use of an Activity Definition.

Field	Type	Meaning
activity	ActivityDefinitionReference	Reusable activity meaning
epoch	StudyEpochReference	Participant period in which it occurs
encounter	EncounterDefinitionReference?	Visit/contact grouping
timing	TimingConstraint	Anchor, offset, window, repetition, or trigger
applicability	ApplicabilityRule	Which participants require the placement
requiredness	ActivityRequirement	Required, conditional, or optional meaning

Activity Occurrence

Field	Type	Meaning
identity	ActivityOccurrenceIdentity	Stable occurrence identity
participant	StudyParticipantReference	Participant for whom it occurred
placement	ActivityPlacementReference?	Planned intent being realized
actualTiming	ClinicalTimeInterval	When it actually happened
performer	StudyTeamParticipationReference?	Responsible performer
disposition	OccurrenceDisposition	Performed, partial, missed, cancelled, not applicable
outputs	ActivityOutputReference[]	Produced observations, materials, decisions, evidence

Observation

An Observation is a recorded assertion—not a generic mutable value.

class Observation<TValue> {
  identity: ObservationIdentity;
  subject: ObservationSubject;
  characteristic: ClinicalConcept;
  value: TValue;
  effectiveTime: ClinicalTime;
  method?: ObservationMethod;
  source: DataOrigin;
  governingDefinition: DefinitionRevisionReference;
  terminology?: TerminologyReleaseReference;
  revisionHistory: ObservationRevision<TValue>[];

  correct(correction: ObservationCorrection<TValue>): ObservationCorrected;
  invalidate(reason: InvalidationReason): ObservationInvalidated;
}

Specializations

• EdcDatapoint
• eCOAResponse
• LaboratoryResult
• DeviceMeasurement
• ImagingRead
• ClinicalAssessment
• SupplyTemperatureObservation

They share observation semantics while retaining domain-specific behaviour.

Rules

• Definition, placement, schedule item, occurrence, and observation remain distinct.
• Missing, unknown, not applicable, withheld, and not collected are explicit meanings.
• Corrections retain the prior assertion, actor, time, and reason.
• An occurrence may exist without structured observations.
• A received external observation retains its original source and transformation provenance.
• Display order does not define clinical timing.