Question

Explain how cardinality is used as a control in the REA model.

Answer 1

The REA data model was developed specifically
for use in designing accounting information
systems.
– Focuses on business semantics underlying an
organization’s value chain activities.
– Provides guidance for:
• Identifying the entities to be included in a database.
• Structuring the relationships among the entities.

A cardinality describes the nature of the
relationship between two entities.
– It indicates how many instances of one entity can be linked to a specific instance of another entity. It is not a “one size fits all” world for relationships and cardinalities. The cardinalities between two entities can vary based on how the particular company does business. In other words, the choice of cardinalities is not arbitrary. It reflects facts about the organization that are obtained during the requirements definition stage of the database design process. An exception could occur if the first event is not required for the second event to
occur.