The Psychology of Quality and More

A Toolbook for Quality Improvement and Problem Solving (contents)

Hierarchies

The Quality Toolbook > Tools for Applications > Tool types > Hierarchies

Description | Examples

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Non-numeric information often arrives in, or can be broken down into, discrete and relatively independent chunks. Visual tools help to discover and organize these chunks, showing the various types of relationships between them.

Description

Hierarchies are used in several tools, where they are used to either break down information into component parts or to build up detailed data into an organized structure. Hierarchies are often called trees and are characterized by their parent-child organization, as shown below. A parent item has any number of children, whilst a child has only one parent. At the top of the hierarchy is the root, or one parent with no parents of its own, whilst at the bottom of the hierarchy are leaves, or individual items with no children of their own.

Fig. 1. Hierarchy

Examples

• Tree Diagram

• Cause-Effect Diagram

• Fault Tree Analysis (FTA)

• Process Decision Program Chart (PDPC)

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