Theory of Constraints Handbook - James Cox Iii [434]
The TP tools act as guides for the decision-making process as well as representations of logic. They embrace problem structuring or representational tools, such as the Current Reality Tree (CRT), the Evaporating Cloud (EC), and the Future Reality Tree (FRT), and tools such as the Prerequisite Tree (PRT) and Transition Tree (TRT) that facilitate effective implementation.
The TP were developed to facilitate beneficial change, which in most circumstances also requires, or relates to, overcoming resistance to change. They guide the user to find answers to basic questions relating to the change sequence, namely, What to Change? What to Change to? and How to Cause the Change? For example, the CRT helps identify what, in the system, needs to be changed. The EC is then used to gain an understanding of the conflict within the system environment, or of the reality that may be causing the conflict. The EC also provides ideas of what can be changed to break the conflict and resolve the core problem. The FRT used in concert with the Negative Branch Reservation (NBR; a sub-tree of the FRT) takes these ideas for change and demonstrates that the new reality created would lead, in fact, to resolution of the unsatisfactory systems conditions and not cause new ones. The PRT determines obstacles to implementation and the desired sequence to overcome them, and the TRT is a means by which to create a step-by-step change implementation plan. Four preliminary steps usually precede such discussion, namely, What the system is, What its goal is, How progress toward the goal will be measured,2 and Why the change is needed. In addition, following these are the steps to sustain the change and to develop a process of ongoing improvement (POOGI).3 Dettmer (2007) provides the Intermediate Objectives (IO) map for this purpose, while others follow the Business System Model of Cox et al. (2003) and the Three-Cloud Method (Button, 1999, 2000), and yet others describe these steps as preliminary to the Five Focusing Steps (5FS; Scheinkopf, 1999).
The various TP tools subsequently have been further developed to improve or simplify the building of logic diagrams. While the TP were designed and introduced as an integrated set of problem-solving tools, we know also that by using the TP tools, individually or in concert, an organization can develop and implement change solutions successfully (Scheinkopf, 1999).
The TP’s embrace and are constructed from three basic logic building blocks (Scheinkopf, 1999). Two of the building blocks manifest cause-effect thinking through employing either sufficiency-based if-then logic or necessity-based in order to . . . we must have . . . logic. The CRT, FRT, and TRT are sufficiency-based logic diagrams, whereas the EC and PRT are necessity-based logic structures. The third building block manifests as a set of rules governing the logic-in-use and provides a protocol for establishing and challenging the existing cause-effect thinking and logic. It does so through the seven Categories of Legitimate Reservation (CLR) (Goldratt, 1994, Chapter 15; Noreen et al., 1995; Dettmer, 1998; Scheinkopf, 1999, Chapter 4. Chapter 25, Appendix B of this Handbook lists and describes the CLR.) that legitimize, depersonalize, and depoliticize any challenges to current thinking. Such rules are used to add rigor to the modeling process and to check the validity of the constructed logic relations as logic tree diagrams. The result is a logical, structured, and rigorous process to guide managerial decision-making, utilizing the intuition and knowledge of those involved and invoking challenges to existing thinking using the protocols of the CLR.
The next section provides a description of each TP tool, judged to be sufficient