Hierarchy

• Hierarchy is an arrangement of items (objects, names, values, categories, etc.) in which the items are represented as being "above," "below," or "at the same level as" one another.

Hierarchy Types

• Hierarchy types include Balanced, Unbalanced, and Ragged Hierarchies.

Balanced Hierarchies

• In a balanced hierarchy, each branch of the tree contains the same number of levels, and the parent of every member comes from the level immediately above. This is an example of a balanced hierarchy.

Unbalanced Hierarchies

• In an unbalanced hierarchy, each branch of the tree can descend to a different level, so it has leaf nodes at more than one level.
• The parent of every member comes from the level immediately above.

Ragged Hierarchies

• In a ragged hierarchy, the logical parent of at least one member does not come from the level immediately above, but a level higher up. In the following example, city information for Washington DC relates to the country level, not the state level.

Examples of Hierarchy