T h e o r y o f C o n s t r a i n t s T h i n k i n g To o l s

ROOT CAUSE ANALYSIS WORKSHOP

Presented by Kelsey van Haaster and Tavis Ashton-Bell

kelseyvh@Thoughtworks.com tavisab@gmail.com

OVERVIEW

Very Brief intro to the Theory of Constraints ( 5 minutes)

A worked example of a Current Reality and a Future Reality Tree (15 minutes)

Introducing the ToC thinking tools (5 minutes)

Step by step practice on a problem of your choosing - (Team activity) (20 minutes)

Sharing back to the group (10 minutes)

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A VERY BRIEF INTO TO THE THEORY OF CONSTRAINTS

Developed by Dr Eliyahu Goldratt, Physicist and Management Specialist

Author of The Goal, Beyond the Goal and It’s not luck

A philosophy which seeks to understand a system through the identification of cause and effect

Applicable in any domain

ToC thinking tools are based on this philosophy and:

Are both systemic and systematic in approach

Produce robust, logically sound analysis and solutions

What to change

What to change to

How to change

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BENEFITS

Using a picture takes the focus off expertise level and promotes teamwork and common understanding. A CRT provides a visual thought process that can easily be scrutinised for validity and edited for increased buy-in of the problem & priority. Can uncover unrecognised needs. Gets you started on the one thing that has the most impact on the system as a whole

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A WORKED EXAMPLE OF A KNOWN PROBLEM AND SOLUTION

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NOTATION (SIMPLIFIED SUBSET)

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UDE

Undesirable effect

Precondition

Current Reality Tree

Precondition

Future Reality Tree

DE

Desirable effect

IE

Intermediate effect

Action

Action

Goal

Goal

Edge

AND operator

Both

Solution

Solution

THE PROBLEM WITH SOFTWARE PROJECTS

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Relevant undesirable effects and a precondition

The Problem to solve

A WORKED EXAMPLE - BUILDING THE TREE (1)

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Which of our UDE (s) explain the problem ?

Clarity Reservation Is the cause and effect relationship clear?

Entity Existence Reservation Do the cause and effect entities really exist?

Causality Existence Reservation Is the causal link valid?

Predicated Effect Existence Reservation there is no other effect which negates this one being cause

Insufficient Cause Reservation An additional non trivial cause must exist to explain the observed effect

Additional Cause Reservation - Neither cause can account for the effect alone

Tautology - A cause and effect relationship is redundant

Add the contributing UDE’s and apply the categories of

legitimate reservation

WORKED EXAMPLE - BUILDING THE TREE (2)

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Add the contributing UDE’s and apply the

categories of legitimate reservation

BUILDING THE TREE (3) ADDITIONAL CAUSES

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BUILDING THE TREE LOOKING FOR SINGLE CAUSES (4)

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THE COMPLETE TREE (5)

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FINDING THE SOLUTION

The generation of or more solutions are accomplished using the concept of the Cloud.

The underlying assumption behind the concept of the Cloud is that there are no conflicts in nature – only erroneous assumptions.

The cloud provides a structured approach to identifying and then testing underlying assumptions.

A quick example: Asking for a pay rise

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THE CLOUD

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ADDING IN SOME UNDERLYING ASSUMPTIONS

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INJECTING A POSSIBLE SOLUTION

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BACK TO OUR PROBLEM

There are many potential solutions, however lets use a widely understood one to demonstrate the Future Reality Tree as a way of testing and presenting the idea

First the solution:

We are uncovering better ways of developing software by doing it and helping others do it.

Through this work we have come to value:

Individuals and interactions over processes and tools

Working software over comprehensive documentation

Customer collaboration over contract negotiation

Responding to change over following a plan

That is, while there is value in the items on the right, we value the items on the left more.

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BUILDING A FUTURE REALITY TREE

At its simplest level an FRT is a CRT with all the Undesirable Effects transformed into Desirable Effects and the problem statement turned into a goal.

We Build an FRT by injecting our solutions into our Current Reality Tree and evaluating whether the solution transforms Undesirable Effects into Desirable ones.

This usually requires some refinement and rewording as you go

Let’s try this with our example problem

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SOLUTIONS TO BE INJECTED INTO OUR CRT

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BUILDING THE FRT (1)

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The Current RealityThe Future Reality

BUILDING THE FRT (2)

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The Current Reality

The Future Reality

BUILDING THE FRT (3)

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The Current Reality

The Future Reality

BUILDING THE FRT (4)

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The Current Reality

The Future Reality

THE COMPLETED TREE

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We are uncovering better ways of developing software by doing

it and helping others do it.

Through this work we have come to value:

Individuals and interactions over processes and tools

Working software over comprehensive documentation

Customer collaboration over contract negotiation

Responding to change over following a plan

THE TOOLSET

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Tool When to use

Current Reality Tree To understand the root cause(s) of the problem

When there is disagreement about the nature of the problem

When there is disagreement about the extent of the problem

Evaporating Cloud (injection) To resolve conflict To gain agreement about

the nature of a solution

Future Reality Tree To identify a solution To ensure the solution addresses the whole problem

To test the logic behind a solution

Pre-requisite TreeTo identify the pre- conditions for implementing a solution

Transition TreeTo identify the steps required to implement a solution

PROOF READING TOOLS FOR YOUR TREES

Clarity Reservation Is the cause and effect relationship clear?

Entity Existence Reservation Do the cause and effect entities really exist

Causality Existence Reservation Is the causal link valid

Predicated Effect Existence Reservation

Showing that the cause does not result in the initial effect by using another effect

Insufficient Cause Reservation An additional non trivial cause must exist to explain the observed effect

Additional Cause Reservation Neither cause can account for the effect alone

Tautology A cause and effect relationship is redundant

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Categories of Legitimate Reservation Intended to raise valid concerns about cause and effect rigour, without

raising resistance of defensiveness with others

NOW IT’S YOUR TURN

Work in groups of 2 - 4 and create a Current Reality Tree for a problem of your choosing.

You can use sticky notes on a whiteboard, or any software that lets you draw boxes and line.

e.g. Powerpoint, Keynote, Word, even paint

Use the cheat sheet to follow the steps and we will be on hand to help.

At about 10 minutes before the end of the session, we will ask people to share the problem they looked at and any new insights gleaned from the process.

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REFERENCES AND RESOURCESBooks: ToC in General

The Theory of Constraints - E. Goldratt

The Goal: A process of Ongoing Improvement

Critical Chain

Books - ToC Thinking Tools

Isn’t it Obvious

It’s Not Luck

Necessary But Not Sufficient

Thinking for a Change

Web Resources

Thinking for a Change handout - (pdf)

ToC Thinking tools - Wikipedia link

A very comprehensive guide to implementation from Kelvyn Youngman

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