Interrelationship Digraphs

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1. Define Problem or Opportunity

(Problem Statement)

2. Determine Requirements,

Constraints, Gap, and Root Causes

3. Generate and Design Solutions to Meet Needs

4. Evaluate, Prioritize, and Test Solution

Ideas

5. Justify and Plan the

Implementation, Manage Change

Process

Core Steps in System & Process Design and Improvement

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Analysis Tools for Step 2:Establish Needs and Causes

Define Needs, Gaps or Causes

• Listen to the “Voice of the Customer”• Use Cause and Effect Diagrams.

Determine Root Causes

and Key Issues

• Ask WHY 5 Times• Use Interrelationship Digraphs

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Learning Objectives

Upon completing this module, you will be able to:

Understand the purpose and use of the Interrelationship Digraph (ID)

Construct, interpret, and revise an ID

Graphically display the complete pattern of cause and effect relationships within complex sets of issues

Identify root causes and key issues in order to develop effective solutions and action plans

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Interrelationship Digraph

This tool takes complex, multi-variable problems or desired outcomes and explores and displays all of the interrelated factors involved.

It graphically shows the logical (and often causal) relationships between factors.

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Interrelationship Digraph

Allows for “multidirectional” rather than “linear” thinking (“web of causes” not just straight line cause and effect)

Graphically maps out the cause and effect links among all items in complex situations that contains many intertwined factors

Employs the clustering of relationship arrows to indicate the issues/causes that are the most fundamental among all the items

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When to Use an ID

An issue is sufficiently complex that the interrelationship between and among ideas is difficult to determine

Numerical data are not available to identify root causes

There is a feeling that the problem under discussion is only a symptom

Root causes must be identified (KEY)

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Establish Needs and Causes, where often

When you really need to know the root cause(s) and key issues of a problem

Construction Steps

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Step 1: Assemble the Right Team

Step 6: Select Key Items in the Finalized ID

Step 2: Agree Upon an Issue/Problem Statement

Step 3: Display the Completed Cards

Step 4: Draw the Relationship Arrows

Step 5: Review and Revise the First Round ID

Step 7: Draw the final ID

Construction Steps

1. Assemble the Right Team Four to Six members Intimate knowledge of issue

2. Agree Upon an Issue/Problem Statement Various sources: From Scratch, Affinity Diagram, Cause & Effect Diagram

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Construction Steps

3. Display the Completed Cards

• Pre-organized, e.g., by Affinity Diagram headers, plus any additional causes or issues not included in the AD headers

• Random Distribution

• One by one, e.g., clustered

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Construction Steps

4. Draw the Relationship Arrows Ask of each card: “Does this card cause/influence any of the other cards displayed?” Repeat until all cards considered Draw one-way arrows only as the question is repeated

A B

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Construction Steps

5. Review and Revise the First Round ID

• Review by team and non-team members

• Individuals indicate changes and opinions on basic causes

• Incorporate suggested changes that the teams agrees upon

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Construction Steps

6. Select Key Items in the Finalized ID

• Find cards with the highest total # of arrows, then cards with the next highest totals, etc.

• Review all cards for those with predominantly outgoing or incoming arrows

• Apply the “rule of experience” to the items passing the “arrow test”

Root Cause

Root CausePredominantly Outgoing Arrows

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Key Issue

Key IssuePredominantly Incoming Arrows

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Construction Steps

7. Draw the Final ID

Identify the key issues and root causes by double boxing

e.g.

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Interrelationship digraph

Root Cause

Key Issues

Identify Physical differences

Optimize environment

Identify environmental

differences

Optimize equipment

Optimize inputs

Optimize Protocol

Identify time differences

Quantify inputs/outputs

Identify variables only present in the

robotic process

Matrix Format

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1. Lack of family consensus on location

2. Ineffective Travel Agent

3. Bad weather

5. Too much to do

6. Expect too much from it

7. Too little to do

9. Bored kids

1 2 3 4 5 6 7 8 9 Out In Total

6 1 7

5 2 7

3 0 3

1 4 5

2 3 5

2 4 6

78. No time for research into location 0 7

1 5 6

4. We can’t relax 0 8 8

What are the barriers to a great vacation?

Root Cause Key Issues

Advantages

The key issues and root causes in problem solving become readily apparent

Explanation of complex issues to others is simplified

As further information is added, it is easy to update

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Disadvantages

Despite appearances, constructing an adequate diagram is surprisingly difficult

If the diagram is too complicated, it becomes difficult to understand and important factors might be overlooked

If the factors are expressed too simply, the arrows may point in many misleading directions.

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Always use a noun and a verb to succinctly define the factor

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Thank You