Theory of Constraints Handbook - James Cox Iii [435]
The TP Tools
The Current Reality Tree (CRT)
The CRT is a sufficiency (if-then) logic-based tool used to identify and describe cause-effect relationships that may help to determine core problems that cause the undesirable effects (UDEs) of the system (Cox et al., 2003; Sullivan et al., 2007). The CRT is designed to answer the question, What to Change? taking care to avoid actions that merely deal with symptoms. This tool is a particularly effective tool if the symptoms are caused by a policy as opposed to a physical constraint of the existing system. A useful variant is the Communications Current Reality Tree (CCRT; Scheinkopf, 1999; Chapter 25, this volume).
The Evaporating Cloud (EC)
Policy constraints identified in the CRT can often be viewed as a conflict or dilemma between two opposing actions. The TP tool for such situations is the Evaporating Cloud (EC), referred to by some as the Conflict Resolution Diagram (CRD; Dettmer, 1999). The EC is used for solving problems—using necessity-based (in order to, we must . . .) logic—that may arise not only from the seeming irreconcilability of opposing actions, attitudes, and behaviors, but also from what may be regarded as a chronic conflict of competing actions, conflict of interest, or as intractable dilemmas of a political, policy, or ethical nature.
Though the EC process frames the problem, for example, as starting with two diametrically opposed actions or views, engaging in the process also implicitly assumes these matters can be resolved by a win-win solution to generate the system goal or objective A, via the attainment of necessary intermediate states, B and C. In order to find such a solution, we elicit those assumptions or reasons why the relationships are thought to hold. Some of these assumptions may be shown as annotations in the “thought bubbles” on the EC diagram (Fig. 23-1).
Often when the assumptions are surfaced and articulated, they may be seen to be false or weak, and the conflict represented by the cloud evaporates. Where assumptions are recognized as valid, they may be addressed in a manner that invalidates them, reduces their importance or impact, and allows for a resolution of the conflict. We develop a list of such assumptions and the accompanying “injections” that may be used to “attack” or address those assumptions to resolve the conflict. Indeed, the EC diagram may provide a basis for insights about the nature of root causes and the core problem identified in our CRT. Specialized versions of the EC include the Generic Evaporating Cloud (GEC), the 3-UDE Cloud, and the Core Conflict Cloud. See Chapters 24 and 25 for a detailed development of the EC.
FIGURE 23-1 The EC diagram.
The Future Reality Tree (FRT)
The FRT process, in contrast to the CRT, begins with the identification of actions, conditions, or solutions of choice, what Goldratt collectively names as “injections,” and then through the mapping of sufficiency-based logic relations, checks whether the causal links will lead to what we have decided are desirable outcomes, that is, the removal or closing of Dettmer’s “mismatches.” As Rizzo (2001, 14) states, the construction of the FRT can be viewed as a “what-if exercise,” helping to identify what actions and conditions will be necessary and sufficient to bring about desirable effects or change, and whether or not additional UDEs will also emerge from our actions (Kendall, 1998, 39).
Subtrees may be constructed in this process whenever someone raises a “Yes, but . . .” doubt or type of reservation. Such situations indicate that the “objector” has thought of a possible negative side effect of the proposed solution. Rather than brush the comments aside or abandon the proposal, we are encouraged by the TOC philosophy to explore ways of adapting the proposal to avoid such negative side effects while still