documentation:cdm:measurement
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documentation:cdm:measurement [2016/05/24 23:30] cgreich |
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| ==== Conventions ==== | ==== Conventions ==== | ||
| * Measurements differ from Observations in that they require a standardized test or some other activity to generate a quantitative or qualitative result. For example, LOINC 1755-8 concept_id 3027035 'Albumin [Mass/time] in 24 hour Urine' is the lab test to measure a certain chemical in a urine sample. | * Measurements differ from Observations in that they require a standardized test or some other activity to generate a quantitative or qualitative result. For example, LOINC 1755-8 concept_id 3027035 'Albumin [Mass/time] in 24 hour Urine' is the lab test to measure a certain chemical in a urine sample. | ||
| - | * Even though each Measurement requires to have a result, the fields value_as_number and value_as_concept_id are not mandatory. When the result is missing, the Measurement record might represent an order or the result was not captured in the source data (missing data). | + | * Even though each Measurement always have a result, the fields value_as_number and value_as_concept_id are not mandatory. When the result is not known, the Measurement record represents just the fact that the corresponding Measurement was carried out, which in itself is already useful information for some use cases. |
| + | * Note that the value of value_as_concept_id may be provided through mapping from a source Concept which contains the result (like positive pregnancy test codes). In those situations, the CONCEPT_RELATIONSHIP table in addition to the "Maps to" record contains a second record with the relationship_id set to "Maps to value". | ||
| * Valid Measurement Concepts (measurement_concept_id) belong to the 'Measurement' domain, but could overlap with the 'Observation' domain. This is due to the fact that there is a continuum between systematic examination or testing (Measurement) and a simple determination of fact (Observation). When the Measurement Source Value of the code cannot be translated into a standard Measurement Concept ID, a Measurement entry is stored with only the corresponding source_concept_id and measurement_source_value and a measurement_concept_id of 0. | * Valid Measurement Concepts (measurement_concept_id) belong to the 'Measurement' domain, but could overlap with the 'Observation' domain. This is due to the fact that there is a continuum between systematic examination or testing (Measurement) and a simple determination of fact (Observation). When the Measurement Source Value of the code cannot be translated into a standard Measurement Concept ID, a Measurement entry is stored with only the corresponding source_concept_id and measurement_source_value and a measurement_concept_id of 0. | ||
| * Measurements are stored as attribute value pairs, with the attribute as the Measurement Concept and the value representing the result. The value can be a Concept (stored in value_as_concept), or a numerical value (value_as_number) with a Unit (unit_concept_id). | * Measurements are stored as attribute value pairs, with the attribute as the Measurement Concept and the value representing the result. The value can be a Concept (stored in value_as_concept), or a numerical value (value_as_number) with a Unit (unit_concept_id). | ||
documentation/cdm/measurement.txt · Last modified: 2017/09/25 15:02 by clairblacketer
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