Editing Data model (section)

=== The role of data models ===
[[File:3-4 Data model roles.svg|thumb|320px|How data models deliver benefit<ref name="MW99">Matthew West and Julian Fowler (1999). [https://sites.google.com/site/drmatthewwest/publications/princ03.pdf Developing High Quality Data Models]. The European Process Industries STEP Technical Liaison Executive (EPISTLE).</ref>]]
The main aim of data models is to support the development of [[information system]]s by providing the definition and format of data. According to West and Fowler (1999) "if this is done consistently across systems then compatibility of data can be achieved. If the same data structures are used to store and access data then different applications can share data. The results of this are indicated above. However, systems and interfaces often cost more than they should, to build, operate, and maintain. They may also constrain the business rather than support it. A major cause is that the quality of the data models implemented in systems and interfaces is poor".<ref name="MW99"/>
* "Business rules, specific to how things are done in a particular place, are often fixed in the structure of a data model. This means that small changes in the way business is conducted lead to large changes in computer systems and interfaces".<ref name="MW99"/>
* "Entity types are often not identified, or incorrectly identified. This can lead to replication of data, data structure, and functionality, together with the attendant costs of that duplication in development and maintenance".<ref name="MW99"/>
* "Data models for different systems are arbitrarily different. The result of this is that complex interfaces are required between systems that share data. These interfaces can account for between 25–70% of the cost of current systems".<ref name="MW99"/>
* "Data cannot be shared electronically with customers and suppliers, because the structure and meaning of data has not been standardized. For example, engineering design data and drawings for process plant are still sometimes exchanged on paper".<ref name="MW99"/>
The reason for these problems is a lack of standards that will ensure that data models will both meet business needs and be consistent.<ref name="MW99"/>

A data model explicitly determines the structure of data. Typical applications of data models include database models, design of information systems, and enabling exchange of data. Usually, data models are specified in a data modeling language.[3]