Data Element
A data element is a single unit of data that in a certain context is considered indivisible. It is a unit of data representing a single fact about a type of object (object class) in the natural world. (For example, a one character code with allowed values of "M" or "S" representing the marital status attribute of an "employee" object class.) It cannot be decomposed into more fundamental segments of information that have useful meanings within the scope of its application.
Data elements are electronic or written representations of the properties of natural‑world object classes.
Classification for Data Elements, ISO/IEC 11179-2, provides procedures and techniques for associating data element concepts and data elements with classification schemes for object classes, properties and representations.
Contents |
Anatomy of a data element
A data element is composed of the following:
The core unit of interest to most users of an MDR are data elements. These elements describe the basic container of data. When creating definitions for new elements the following guidelines should be followed:
Definitions should not refer to terms or concepts that might be misinterpreted by others or that have different meanings based on the context of a situation. Definitions should not contain acronyms that are not clearly defined or linked to other precise definitions.
Definitions
- Precise - The definition should use words that have a precise meaning. Try to avoid words that have multiple meanings or multiple word senses.
- Concise - The definition should use the shortest description possible that is still clear.
- Non Circular - The definition should not use the term you are trying to define in the definition itself. This is known as a circular definition.
- Distinct - The definition should differentiate a data element from other data elements. This process is called disambiguation.
- Unencumbered - The definition should be free of embedding rationale, functional usage, domain information, or procedural information.
Definition Explained
Here is the definition of "person" data element as defined in the www.w3c.org Friend of a Friend specification:
- Person: A person.
Although most people do have an intuitive understanding of what a person is, the definition has much room for improvement. The first problem is that the definition is circular. Note that this definition really does not help most readers and needs to be clarified.
Here is the definition of the "Person" Data Element in the Global Justice XML Data Model 3.0:
- Person: Describes inherent and frequently associated characteristics of a person.
Note that once again the definition is still circular. Person should not reference itself. The definition should use terms other than person to describe what a person is.
Here is a more precise but shorter definition of a person:
- Person: An individual human being.
Note that it uses the word individual to state that this is an instance of a class of things called human being. Technically you might use "homo sapiens" in your definition, but more people are familiar with the term "human being" than "homo sapiens," so commonly used terms, if they are still precise, are always preferred. Sometimes your system may have cultural norms and assumptions in the definitions. For example if your "Person" data element tracked characters in a science fiction series that included aliens you may need a more general term other than human being.
- Person: An individual of a sentient species.
Data Element example
|
E.g. Person - body height (self reported), total centimeteres NN[NN]. Data Element Concept = Person - body height Qualifier = (self reported) Value domain = Total centimeters NN[N].N |
Impacts on naming standards on Registration authorities
These procedures and techniques shall assist Registration Authorities in applying classification schemes that enable them to perform activities such as:
- analyse object classes, data element concepts, and data elements
- make comparisons within the following categories: object classes, data element concepts, and data elements;
- reduce the variety of data element concepts and data elements
- define and identify data element concepts and data elements unambiguously
- assist in the analysis of data elements for the purpose of assigning registration status
- retrieve data element concepts and data elements from a data element registry;
- recognize relationships among data element concepts and data elements
