> ## Documentation Index > Fetch the complete documentation index at: https://docs.metriport.com/llms.txt > Use this file to discover all available pages before exploring further. # EvidenceVariable > The EvidenceVariable resource describes a "PICO" element that knowledge (evidence, assertion, recommendation) is about. ## Properties | Name | Required | Type | Description | | -------------------------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------- | | url | No | uri | Canonical identifier for this evidence variable, represented as a URI (globally unique) | | identifier | No | [Identifier](/medical-api/fhir/data-types/identifier)\[] | Additional identifier for the evidence variable | | version | No | string | Business version of the evidence variable | | name | No | string | Name for this evidence variable (computer friendly) | | title | No | string | Name for this evidence variable (human friendly) | | shortTitle | No | string | Title for use in informal contexts | | subtitle | No | string | Subordinate title of the EvidenceVariable | | status | Yes | code | draft / active / retired / unknown | | date | No | dateTime | Date last changed | | publisher | No | string | Name of the publisher (organization or individual) | | contact | No | [ContactDetail](/medical-api/fhir/data-types/contactdetail)\[] | Contact details for the publisher | | description | No | markdown | Natural language description of the evidence variable | | note | No | [Annotation](/medical-api/fhir/data-types/annotation)\[] | Used for footnotes or explanatory notes | | useContext | No | [UsageContext](/medical-api/fhir/data-types/usagecontext)\[] | The context that the content is intended to support | | jurisdiction | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[] | Intended jurisdiction for evidence variable (if applicable) | | copyright | No | markdown | Use and/or publishing restrictions | | approvalDate | No | date | When the evidence variable was approved by publisher | | lastReviewDate | No | date | When the evidence variable was last reviewed | | effectivePeriod | No | [Period](/medical-api/fhir/data-types/period) | When the evidence variable is expected to be used | | topic | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[] | The category of the EvidenceVariable, such as Education, Treatment, Assessment, etc. | | author | No | [ContactDetail](/medical-api/fhir/data-types/contactdetail)\[] | Who authored the content | | editor | No | [ContactDetail](/medical-api/fhir/data-types/contactdetail)\[] | Who edited the content | | reviewer | No | [ContactDetail](/medical-api/fhir/data-types/contactdetail)\[] | Who reviewed the content | | endorser | No | [ContactDetail](/medical-api/fhir/data-types/contactdetail)\[] | Who endorsed the content | | relatedArtifact | No | [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact)\[] | Additional documentation, citations, etc. | | type | No | code | dichotomous / continuous / descriptive | | characteristic | Yes | EvidenceVariableCharacteristic | What defines the members of the evidence element | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - description | No | string | Natural language description of the characteristic | | - definition\[x] | Yes | Reference\<[Group](/medical-api/fhir/resources/group)>, canonical, [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Expression](/medical-api/fhir/data-types/expression), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition) | What code or expression defines members? | | - usageContext | No | [UsageContext](/medical-api/fhir/data-types/usagecontext)\[] | What code/value pairs define members? | | - exclude | No | boolean | Whether the characteristic includes or excludes members | | - participantEffective\[x] | No | dateTime, [Period](/medical-api/fhir/data-types/period), [Duration](/medical-api/fhir/data-types/duration), [Timing](/medical-api/fhir/data-types/timing) | What time period do participants cover | | - timeFromStart | No | [Duration](/medical-api/fhir/data-types/duration) | Observation time from study start | | - groupMeasure | No | code | mean / median / mean-of-mean / mean-of-median / median-of-mean / median-of-median | ## Search Parameters | Name | Type | Description | Expression | | --------------------- | --------- | --------------------------------------------------------------------------------------- | --------------------------------- | | composed-of | reference | What resource is being referenced | EvidenceVariable.relatedArtifact | | context | token | A use context assigned to the evidence variable | EvidenceVariable.useContext.value | | context-quantity | quantity | A quantity- or range-valued use context assigned to the evidence variable | EvidenceVariable.useContext.value | | context-type | token | A type of use context assigned to the evidence variable | EvidenceVariable.useContext.code | | date | date | The evidence variable publication date | EvidenceVariable.date | | depends-on | reference | What resource is being referenced | EvidenceVariable.relatedArtifact | | derived-from | reference | What resource is being referenced | EvidenceVariable.relatedArtifact | | description | string | The description of the evidence variable | EvidenceVariable.description | | effective | date | The time during which the evidence variable is intended to be in use | EvidenceVariable.effectivePeriod | | identifier | token | External identifier for the evidence variable | EvidenceVariable.identifier | | jurisdiction | token | Intended jurisdiction for the evidence variable | EvidenceVariable.jurisdiction | | name | string | Computationally friendly name of the evidence variable | EvidenceVariable.name | | predecessor | reference | What resource is being referenced | EvidenceVariable.relatedArtifact | | publisher | string | Name of the publisher of the evidence variable | EvidenceVariable.publisher | | status | token | The current status of the evidence variable | EvidenceVariable.status | | successor | reference | What resource is being referenced | EvidenceVariable.relatedArtifact | | title | string | The human-friendly name of the evidence variable | EvidenceVariable.title | | topic | token | Topics associated with the EvidenceVariable | EvidenceVariable.topic | | url | uri | The uri that identifies the evidence variable | EvidenceVariable.url | | version | token | The business version of the evidence variable | EvidenceVariable.version | | context-type-quantity | composite | A use context type and quantity- or range-based value assigned to the evidence variable | EvidenceVariable.useContext | | context-type-value | composite | A use context type and value assigned to the evidence variable | EvidenceVariable.useContext | ## Inherited Properties | Name | Required | Type | Description | | ----------------- | -------- | ------------------------------------------------------ | ------------------------------------------------------ | | id | No | string | Logical id of this artifact | | meta | No | [Meta](/medical-api/fhir/data-types/meta) | Metadata about the resource | | implicitRules | No | uri | A set of rules under which this content was created | | language | No | code | Language of the resource content | | text | No | [Narrative](/medical-api/fhir/data-types/narrative) | Text summary of the resource, for human interpretation | | contained | No | Resource\[] | Contained, inline Resources | | extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored | To view the FHIR specification for this resource, see [EvidenceVariable](https://www.hl7.org/fhir/StructureDefinition/EvidenceVariable).