description: The primary measure of variance/uncertainty of the value (the square root of the sum of the squares of the differences between all data points and the mean). package_name: rs/hl7.fhir.core derivation: constraint name: Standard Deviation (same units as the quantity) type: Extension elements: extension: index: 0 slicing: slices: extension: match: {} schema: {index: 0} max: 0 url: type: uri pattern: {type: uri, value: 'http://hl7.org/fhir/StructureDefinition/iso21090-uncertainty'} index: 1 value: choices: [valueDecimal] index: 3 valueDecimal: {type: decimal, choiceOf: value, index: 4} package_version: 1.8.0 extensions: extension: {url: null, max: 0, index: 0} class: extension kind: complex-type url: http://hl7.org/fhir/StructureDefinition/iso21090-uncertainty base: http://hl7.org/fhir/StructureDefinition/Extension version: null required: [value, valueDecimal]