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



We Didn’t Intend That To Happen

A negative branch reservation is a modification of the future reality tree that accounts for new negative outcomes that result from our injections.  It really deserves to be treated as a stand alone component and Dettmer at least has considered it significant enough to give it separate treatment from the future reality tree (1).

The negative branches might be obvious or quite unanticipated.  If they are obvious they will have been verbalized as a reservation – a “yes but” – at some earlier stage and we must deal with the reservation.  Even if unanticipated the process of working through the systematic cause and effect logic will cause them to become apparent.  Once apparent the effect must be removed or mitigated.  This tree allows us to do that in a structured way.  Essentially the potential undesirable outcomes must be “trimmed” or modified by either changing the original injection or maybe adding a further and hopefully lesser injection to account for the trim.

Let’s look at our future reality tree again.

An initially unanticipated negative branch has “grown” as a consequence of one of our injections and a pre-existing neutral effect.  This is interesting, because the neutral effect both previously in the future reality tree and now in isolation is not a problem, but in combination with our new desirable effect resulting from the injection it produces a new undesirable effect.  We need to trim this.

How Do We Trim A Branch?

We trim a negative branch with a new additional injection or maybe a modification of the original injection.  The most likely place to trim the negative branch is prior to the negative effect, it will look like this.

So in the final future reality tree, we will not see the negative branches, only the injections.  Negative branch reservations are very important.  We should endeavor to have our trees scrutinized by the most “argumentative bastards” who are certain to find “holes” if there are holes to be found.

It’s far better to find a hole now in the development stages than 75% through to completion of the execution.  Otherwise it might not only be the plan that is executed!

The negative branch reservation is the tool of choice in gaining understanding and agreement that there will be no undesirable side effects that might develop from our proposed solution to the problem at hand.

If the injections to the future reality tree are simple, then just go ahead and implement them - there is nothing to stop you.  It is indeed possible that just doing the analysis of the current reality tree, the cloud, and future reality tree is sufficient to expose some simple and easy to implement solutions.  However, the nature of most problems in general is that if they were that easy to implement – we would have done it before.  Therefore, if once we have the solutions and nothing happens, then there must be obstacles blocking us.

Overcoming obstacles to implementation of our future reality is the subject of the next tool – the pre-requisite tree.


(1) Dettmer, H. W., (1998) Breaking the constraints to world class performance.  ASQ Quality Press, pp 157-168.

The Webpage Copyright © 2003-2009 by Dr K. J. Youngman

Description: web counter