A workshop delivered at LAST 2015.

1. 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

2. 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)
2

3. 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
3

4. 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
4

5. A WORKED EXAMPLE
OF A KNOWN
PROBLEM AND
SOLUTION
5

6. NOTATION (SIMPLIFIED SUBSET)
6
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

7. THE PROBLEM WITH SOFTWARE PROJECTS
7
Relevant undesirable effects and a precondition
The Problem to solve

8. A WORKED EXAMPLE - BUILDING THE TREE (1)
8
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

9. WORKED EXAMPLE - BUILDING THE TREE (2)
9
Add the contributing
UDE’s and apply the
categories of legitimate
reservation

10. BUILDING THE TREE (3) ADDITIONAL CAUSES
10

11. BUILDING THE TREE LOOKING FOR SINGLE CAUSES (4)
11

12. THE COMPLETE TREE (5)
12

13. 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
13

14. THE CLOUD
14

15. ADDING IN SOME UNDERLYING ASSUMPTIONS
15

16. INJECTING A POSSIBLE SOLUTION
16

17. 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.
17

18. 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
18

19. SOLUTIONS TO BE INJECTED INTO OUR CRT
19

20. BUILDING THE FRT (1)
20
The Current Reality
The Future Reality

21. BUILDING THE FRT (2)
21
The Current Reality
The Future Reality

22. BUILDING THE FRT (3)
22
The
Current
Reality
The
Future
Reality

23. BUILDING THE FRT (4)
23
The
Current
Reality
The
Future
Reality

24. THE COMPLETED TREE
24
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

25. THE TOOLSET
25
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 Tree
To identify the pre-
conditions for
implementing a solution
Transition Tree
To identify the steps
required to implement a
solution

26. 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
26
Categories of Legitimate Reservation
Intended to raise valid concerns about cause and effect rigour, without
raising resistance of defensiveness with others

27. 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.
27

28. REFERENCES AND RESOURCES
Books: 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
28