Overview of Data Model

The data model in Policy Modeling consists of the entities, relationships and attributes that make up the project.

For example, a data model could have:

  • entities: Global, the school, the child, the activity
  • attributes for each entity:
    • Global attributes: the date of assessment, the family's income
    • attributes for the school: the school's type, the school's website
    • attributes for the child: the child's age, the child's student ID
    • attributes for the activity: the cost of the activity, the type of activity
  • relationships between the entities:
    • one-to-many relationship from the Global to the school entity: all instances of the school
    • one-to-many relationship from the Global to the child entity: all instances of the child
    • one-to-many relationship from the Global to the activity entity: all instances of the activity
    • many-to-one relationship from the child entity to the school entity: the child's school
    • many-to-many relationship between the child entity and the activity entity: the child's activities
    • one-to-one relationship between the child entity and the child entity: the child's twin

This would be represented in a data model diagram as shown below.

A data model diagram showing how attributes, entities and relationships connect

 

In data model diagrams:

  • the boxes represent the entities,
  • the lines represent the relationships between the entities
  • * represents a many-relationship type
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