Data element definition
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In metadata, a data element definition is a human readable phrase or sentence associated with a data element within a data dictionary that describes the meaning or semantics of a data element.
Data element definitions are critical for external users of any data system. Good definitions can dramatically ease the process of mapping one set of data into another data set of data. This is a core feature of distributed computing and intelligent agent development.
There several guidelines to that should be followed when creating high-quality data element definitions.
A good definition is:
- 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.
A data element definition is a required property when adding data elements to a metadata registry.
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.
If you are creating a large number of data elements, all the definitions should be consistent with related concepts.
Standards such as the ISO/IEC 11179 Metadata Registry specification give guidelines for creating precise data element definitions.
[edit] Using precise words
Common words such as play or run frequently have many meanings. For example the WordNet database documents over 57 different distinct meanings for the word "play" but only a single definition for the term dramatic play. Fewer definitions in a chosen word's dictionary entry is preferable. This minimizes misinterpretation related to a reader's context and background. The process of finding a good meaning of a word is called Word sense disambiguation.
[edit] Examples of definitions that could be improved
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. Note that this definition really does not help most readers and needs to be clairified.
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 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.
Alldhow the term is also used in the case of some specific fictional alien beings so the following is more correct.
Person: An individual of a sentient species.
Synonyms of "sentient" could be "thinking" or "self-conscious".
