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Current Reality Tree (CRT)

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Current Reality Tree (CRT)

When using the Thinking Processes, the first of 3 questions you should ask  is:

  • "What to change?"

It is the equivalent of the first step of the five step Process Of On Going Improvement: "Identify the Constraint?" However, since the Thinking Processes are usually used when the constraint is not a physical resource, you can rarely use physical evidence like work in process (WIP) to identify the constraint.

Instead, you start with the evidence that is available: the negative effects that are apparent within the system. Examples of negative effects would be things such as:
- frequently shipping orders late
- excessive amounts of inventory
- lead times that are increasing
- poor human relations within the organization

Goldratt calls these "Undesirable Effects" or UDEs. The key is to realize that the UDEs are not the "real" problem—they are only the visible effects of the real or "core" problem. The challenge is to map out the interrelated web of cause-and-effect that links the undesirable effects together. Once completed, one is generally able to identify the "core problem" near the bottom of the logical map.

This map is known as a "Current Reality Tree." Once properly constructed, you know what to change.

For more information on the Thinking Processes, read the following:

  • It's Not Luck by Goldratt (North River Press, 1994)
  • Management Dilemmas, The Theory of Constraints Approach to Problem Identification and Solutions by Schragenheim (The St. Lucie Press, 1999)
  • Thinking for a Change, Putting the TOC Thinking Processes to Use by Sheinkopf (The St. Lucie Press, 1999).

"The biggest enemy of thinking is complexity, for that leads to confusion. When thinking is clear and simple, it becomes more enjoyable and effective."


Dr. Edward  de Bono, Six Thinking Hats, (Little, Brown and Company, 1985)