Theory of Constraints Handbook - James Cox Iii [501]
Constructing a negative branch is simply using the rules of cause and effect to clarify, validate, and resolve a concern over a potential negative ramification of an idea. The major steps are:
1. Write the idea as an entity. If there are multiple elements of the idea, try to write each element as a separate entity. Often, it is just one or two aspects of the idea that are responsible for the concern and this will help you illuminate only the problematic elements of the idea.
FIGURE 25-8 Simple NBR.
2. Make a list of the pros (benefits) and cons (concerns) of the idea. Write the negative outcomes that you are predicting as entities—these are the predicted UDEs.5 Again, try to write each element as a separate entity. Your list of cons of the idea may contain two types of concerns:
a. The first type of concern is consequences that would occur once the idea has been implemented. This is the type of concern that the NBR addresses.
b. The other type of concern is an obstacle. In this case, the concern is not with the idea itself, but rather with things that would get in the way of implementing it. The TOC TP tool that is used to deal with obstacles is the Prerequisite Tree (PRT), which will be described later in this chapter.6
3. Using the mapping protocol discussed earlier in this chapter, connect the injection entity (or entities) using cause-and-effect logic to the predicted UDEs. If you are predicting several UDEs, you may choose to build a single NBR that would encompass some or all of the predicted UDEs, or a separate NBR for each predicted UDE.
4. Check the validity of the cause-and-effect relationship and make adjustments so that it reflects your full hypothesis. This effort will likely lead you to add additional entities and layers along the way, as you make your concern clearer and clearer through the mapping process. Refer to the simple checking process discussed earlier in the chapter.
a. Verify the existence of the causal entity. An NBR is triggered by some aspect of the current reality that, when combined with the future that is going to be created, will hypothetically cause the undesirable consequences. What is that condition, and does it really exist?
b. Validate the cause-and-effect connection between the hypothesized cause and the predicted undesirable consequence. There are usually simple “mind-experiments” you can do, which would either prove the hypothesis wrong or add confidence in its validity.
c. Don’t be surprised if you find that a key assumption you were making was actually incorrect, and you discover that the idea would not (or most probably would not) lead to the negative outcome with which you were initially concerned.
5. Now it is time to “trim the negative branch.” Identify the place in the tree where the transition from “neutral” to “negative” occurs. In Fig. 25-8, this would be where entities 7 and 3 cause entity 8. It is at this intersection where we identify an additional idea that, if implemented, would either prevent 8 from occurring, or even replace 8 with an effect that would become an additional benefit of the solution. Check to make sure that this new, added injection does not lead to more ramifications that are negative. If it does, either replace it with a different injection or add an additional injection to trim the new negative branch.
In Chapter 24, Oded Cohen provides detailed step-by-step instructions for constructing and solving negative branches. A great example of a negative branch is in Chapter 8 of Eli Goldratt’s book, It’s Not Luck (1994, 53–58). I will also provide an example of an NBR later in this chapter, when I review the use of a Strategy & Tactic Tree.
Evaporating Cloud (EC)
A cloud does not know why it moves in just such a direction and at such a speed. It feels an impulsion . . . this is the place to go now. But the sky knows the reason and the patterns behind all clouds, and you will know, too, when you lift yourself high enough to see