A Guide to Implementing the Theory of Constraints (TOC)





Next Step



Bottom Line


Supply Chain

Tool Box



& More ...



Current Reality Tree


3 Cloud Method

Future Reality Tree

Negative Branch

Pre-requisite Tree



Undesirable Effects & Core Problems

Is the term firefighting familiar to you?  The sort, that is, where you always seem to be solving the same problem, solving it for this week and then re-solving again next week also.  When we do this we can be fairly sure that we are addressing the symptoms and not the underlying core issues or drivers of the problem.  Let’s repeat a quote from the introduction to this section; “Our nonsystemic ways of thinking are so damaging specifically because they consistently lead us to focus on low-leverage changes: we focus on symptoms where the stress is greatest.  We repair or ameliorate the symptoms.  But such efforts only make matters better in the short run, at best, and worse in the long run (1).”

We need, maybe desperately need, a way to “drill down” past the surface symptoms into the deeper underlying issues.  Tools for doing this have been very limited indeed.  However the current reality tree is a methodology that allows us to do exactly that.  We start with the symptoms and build back to the core issues.

Looking at it another way, a current reality tree is a statement of an underlying core problem and the symptoms that arise from it.  It maps out a sequence of cause and effect from the core problem to the symptoms.  Most of the symptoms will arise from the one core problem or a core conflict.  Remove the core problem and we may well be able to remove each of the symptoms as well.  Operationally we work backwards from the apparent undesirable effects or symptoms to uncover or discover the underlying core cause (2-4).

The Five Whys

Taiichi Ohno used a similar but less developed methodology called the “five why’s” to uncover the root cause of a problem and to correct it.  The whole Toyota system was built on the practice and evolution of this scientific approach (5).  The “five why’s” is not a superficial tool but one that is expected to dig down to “the ultimate cause ‑ almost always an organizational problem” (6).

“Underneath the ‘cause’ of a problem, the real cause is hidden. In every case, we must dig up the real cause by asking why, why, why, why, why.  Otherwise, countermeasures cannot be taken and problems will not be truly solved (5).”

Unfortunately the methodology doesn’t seem to have been expanded in any formal sense into the broader interrelated cause and effect that can be shown by the current reality tree in Theory of Constraints.

Let’s draw a hypothetical tree to illustrate what we are trying to say.

In this tree several symptoms are mapped back to other common problems and in-turn a single core problem.  Note too, that there is also a neutral effect in the tree.  The neutral effect, while of its self is not negative, it is needed to sufficiently describe the current reality.

The current reality tree is the tool of choice in seeking to gain agreement on the magnitude of the problem that we are investigating and preliminary agreement on the core problem or core conflict that is driving the agreed symptoms or undesirable effects.

Some people prefer to call the symptoms undesirable effects or UDE’s for short.  Let’s do that.

It’s the same tree, just a different terminology.

How do we read such a tree?  From the bottom to the top.  “If ‘cause’ then ‘effect’”.  And where there is an elipse indicating a logical “and” we use “if ‘cause’ and if ‘other cause’ then ‘effect’”.


However we are missing something.  There are no negative feedback loops – so-called vicious cycles.  Some people would go so far as to say that if a current reality tree doesn’t have at least one negative feedback loop then it isn’t a true current reality tree – or that we don’t yet fully understand the true reality of the situation.  Most often the symptoms that arise from the underlying problem, in turn, cause the underlying problem to be worse than if it occurred in isolation.  We saw in the page on people that feedback is an absolutely essential part of any organization; we must include this in our map of the current reality.

We now have a fully described current reality tree.  For example a small child has a reading problem (the symptom) because they are not practicing reading sufficiently (the core problem), which is exacerbated by the difficulty in reading in the first place (the feedback loop).

Core Problem Or Core Conflict

In business situations, however, it is quite possible that we will not be aware of the core problem in the first instance, and instead we will arrive at a core conflict.  Let’s now see how that looks.

In fact we must expect this to be more common.  If we are aware of a core problem and it is within our sphere of control or even influence, then we will try to do something about it.  However, consider the case of a core conflict.  Even when we are in total control of the situation we may let the conflict continue to exist because both of the entities Neutral Effect A and Neutral Effect B are required in order to satisfy something else.  The entities that give rise to all the problems are not perceived to be a problem by themselves.

Constructing a current reality tree is the first and most critical step on the path to improvement, because it makes us verbalize the symptoms and the underlying causes; down layer by layer to the real core problem or conflict.  If we know the real underlying problem and can work out how to overcome it, then we have a very simple and powerful way of overcoming our symptoms.

Although we read a current reality tree from bottom to top, we build it from top to bottom.  An explanation of how to construct a current reality tree is here.

Most often the construction of a current reality tree makes us aware of a number of conflicts, and the tool to use in dealing with conflicts or dilemmas is a cloud.

Let’s have a look at that next.


(1) Senge, P. M. (1990) The fifth discipline: the art and practice of the learning organization.  Random House, pp 64 & 114-115.

(2) Dettmer, H. W., (1997) Goldratt’s Theory of Constraints: a systems approach to continuous improvement.  ASQC Quality Press, pp 62-119.

(3) Dettmer, H. W., (1998) Breaking the constraints to world class performance.  ASQ Quality Press, pp 69-102.

(4) Scheinkopf, L., (1999) Thinking for a change: putting the TOC thinking processes to use. St Lucie Press/APICS series on constraint management, pp 143-169.

(5) Ohno, T., (1978) The Toyota production system: beyond large-scale production.  English Translation 1988, Productivity Press, pp 17-18 & 126-127.

(6) Womack, J. P., Jones, D. T., and Roos, D., (1990) The machine that changed the world.  Simon and Schuster, pg 153.

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