INTRODUCING THE THEORY OF CONSTRAINTS

John F. DeVogt, Ph.D.

Professor of Management Emeritus

Williams School of Commerce

Washington and Lee University

Lexington, Virginia

ABOUT TOC

• TOC applies the methods used by the “hard” sciences to understand and manage the material world of human-based systems including the lives of individuals and organizations.

• TOC comprises a methodology for solving problems and implementing the solution found.

A B

Which System is More Complex?

WHAT IS THE DEFINITION OF A

PROBLEM?

• The traditional definition of a problem is a source of perplexity, distress or irritation.

• The TOC/hard science definition of a problem is a conflict between two conditions/observations. (A basic belief in science is that conflicts do not exist in reality; i.e., something is wrong in our understanding.)

THE THINKING PROCESSES (TP) OF

TOC

• Tools that enable us to use logic to gain an understanding of our reality and then to find ways of improving it.

BASIC CONSTRUCTS OF THE TOC TP

• Causality: “If…then…”

• Necessity: “In order to…I must…”

EXAMPLE OF CAUSALITY

• “IF…THEN…”

I get burned.

I touch a hot stove.

I don't get burned

I touch a hot stove

I am wearing an oven mitt.

EXAMPLE OF NECESSITY

• “In order to…I must…”

Avoid getting

burned.

Do not touch a

hot stove.

Touching a hot stove will

burn me.

PROCESS OF ONGOING

IMPROVEMENT

• No matter what the subject matter, accelerated improvement involves answering the following questions

– What to change?– To what to change?– How to cause a change?

ANSWERING THE QUESTIONS

• What to change? Identify the core conflict or problem (the constraint).

• To what to change? Construct a complete solution.

• How to cause a change? Devise plans for implementing the solution and achieving buy-in where necessary.

EMPLOYING THE TP IN ANSWERING THE QUESTIONS

• What to change? Generic cloud process or Current Reality Tree.

• To what to change? Evaporating Cloud, Future Reality Tree, Negative Branch Reservations.

• How to cause a change? Pre-Requisite Tree, Transition Tree, TOC Buy-In.

TOOL-TYPES OF THE TP

• Necessity:– Generic Cloud

Process

– Evaporating Cloud (EC)

– Pre-Requisite Tree (PRT)

• Causality:– Current Reality Tree

(CRT)

– Future Reality Tree (FRT)

– Negative Branch Reservation (NBR)

– Transition Tree (TrT)

WHAT TO CHANGE?

• Both the CRT and the Generic Cloud Process permit us to state the current situation as a conflict that must be resolved if that situation is to be improved.

The EC Representation of

the Conflict

AThe Objective

BOne Requirement

For A

DOne Requirement

For B

COne Requirement

For A

D’One Requirement

For C

WHAT TO CHANGE TO?

• Uncover and challenge the assumptions underlying the EC structure.

• Find an injection (change in reality) that effectively destroys an assumption behind an arrow in the EC.

• Build a FRT from that injection.

• Subject the FRT to Negative Branch Reservations.

HOW TO CAUSE THE CHANGE ?

• The amended FRT will contain more than one injection. For each of these injections, a PRT will answer the question: what currently prohibits its implementation?

• Each PRT requires actions and these are devised through one or more TrTs.

TOC APPLIED TO BUSINESS

ORGANIZATIONS• Acknowledging and managing the

interdependencies that exist within an organization and among organizations and their effect on flow throughout the entire supply chain.

COST WORLD VIEW vs. THROUGHPUT WORLD VIEW

• Prime measurement: WEIGHT

• Any improvement of any link is an improvement of the chain.

• Global improvement = sum of local improvements.

• Prime measurement: STRENGTH

• Most improvements of most links do not improve the chain.

• Global improvement = improvement in the constraint(s).

THROUGHPUT WORLD VIEW (Strength)

• Suppliers, Vendors Functions, Departments, etc. Customers, markets

PULL

FLOW

WHAT IS THE THEORY OF CONSTRAINTS

(TOC)?

• TO C is the TOC Thinking Processes and the breakthrough, generic solutions that were derived from applying them to specific application areas (e.g., marketing, sales, production, distribution, project management, human relations, etc.).

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