What are Undesirable Effects?

Undesirable Effects (UDEs) in the Thinking Processes/Logical Thinking Process lingo are effects undesirable in/for a system, a process or its stakeholders and clients. The UDEs are hindrances to better throughput or higher performance, or obstacles to achieving the system’s Goal.

In this post I present two “understandings” of the UDEs. The first is ToC’s Thinking Processes, second and later in time UDEs as seen from the Logical Thinking Process perspective.

UDEs in the Theory of Constraints’ Thinking Processes

UDEs are hindrances to better throughput or performance, limiting the system’s throughput or performance at large. UDEs can be obvious symptoms of problems or malfunctions. UDEs are generally well-known by people they concern, thus these people can express and list them easily. What is not so easy is to identify the root cause of all evil.

Theory of Constraints assumes that most Undesirable Effects are the visible effects of a unique or a small number of root causes, the core problem. If the core problem can be identified and eliminated, all related UDEs will disappear. Therefore it is meaningful to focus all energy and limited resources to identify and eliminate the core problem.

UDEs are described in a manner such as: “what causes us the more trouble is…”

UDEs are stated in full sentences in present tense and written in rounded square boxes. UDEs are the “leafs” of a Current Reality Tree (usually on top of it) which describes all UDEs and their relationships, down to a common critical root cause or more likely a small number of critical root causes.

UDEs in the Logical Thinking Process

The Logical Thinking Process (LTP) is a latter development by Bill Dettmer.  From his experience with the Thinking Processes, Bill redefined (refocused) Undesirable Effects as undesirable for the system as a whole. In other words an Undesirable Effect is harming the system, like preventing it to achieve its Goal or limiting the system’s performance. If stated UDEs do not harm the system, they are things that people do not like but are nothing the system would have to care about.

Bill Dettmer is also critical about the “V-shape” stating that most of the problems can be related to a core root cause at the bottom of the V. From his extensive experience, he says that reality proved different many times but because of the V shape dogma, many Toc Thinking Processes practitioners are contriving the logic to fit the model instead of analyzing in a real logical mode.

Theory of Constraints Handbook

The Theory of Constraints Handbook (McGraw-Hill, 2010, page 697) gives definition and guidelines about UDEs:

The UDE is an effect and its existence is indisputable (even though people may argue about its magnitude). It is undesirable—it endangers, reduces, or prohibits achieving a valid need, objective, or even the goal of a system.

The UDE has a clear syntax with clear guidelines:

  • It is a complaint about an ongoing problem that exists in the reality and because of this problem, the system cannot perform better.
  • It should be written in present tense.
  • It should be a complete sentence.
  • It is a description of the state, not an action.
  • It is within your area of responsibility.
  • Something can be done about it.
  • It must not blame someone.
  • It must not be a speculated cause.
  • It must not be a hidden solution to the problem (wishful thinking of solving the problem).
  • It should contain one entity.
  • It should not include its cause in its verbalization.
  • It should be factual and not subjective.

More about so-called “problems” and UDEs: Redefining “problem” (with Goal in mind)


About the author, Chris Hohmann

About the author, Chris Hohmann

View Christian HOHMANN's profile on LinkedIn

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