Theory of Constraints Handbook - James Cox Iii [436]
The Prerequisite Tree (PRT)
Development of the PRT, complementing and building on the FRT, seeks to identify local obstacles, omissions, and conditions that might block the path to the desired outcomes, and then to set new IOs and goals that would equate to overcoming those obstacles. The PRT is often developed by a team, in addressing obstacles that confront them, and hence social practices and power relations embedded in the problem will be considered implicitly, if not explicitly. If the team or working relationships are perceived to be an obstacle, then such issues will usually be raised.
The Transition Tree (TRT)
The development of the final logic structure, the TRT, seeks to identify tasks and actions both necessary and sufficient to meet the IOs of the PRT, to overcome what might go wrong, to provide a rationale and schedule for action, and, as such, to provide what we may regard as a coherent step-by-step implementation plan, and which also accounts for prevailing beliefs, feelings, and norms.
Summary
As we move through the tools, CRT through to TRT, there is generally more involvement from the wider group affected by the problem, or by actions designed to address it. The tools purposefully address successive layers of “resistance” and “buy-in” (Houle and Burton-Houle, 1998; Goldratt, Chapter 20; Lang, Chapter 22), and other issues raised in the broader “change management” literature (Mabin et al., 2001). The CRT may be developed by a smaller group, initially, with buy-in being developed increasingly through the remaining steps of the TP. Likewise, empowerment also develops through the TP. The CRT represents the current situation, enlightening but not necessarily empowering. The PRT and TRT in particular are designed to build collective buy-in, aiding the implementation phase. The end goal and normal outcome of the FRT, NBR, PRT, and TRT is to help people gain a better understanding of the problematic situation and the results of their actions, and to feel empowered through having an agreed course of action.
The next section moves from a consideration of what the TP tools are to a review of the tools-in-use, patterns of use, and opportunities for further use and enhancement of the tools.
The TOC TP Literature
In this section, we review developments to the TOC body of knowledge, particularly the TOC TP as reported in the public domain peer-reviewed literature. In doing so, we also comment on the nature of the TP, vis-à-vis their evolution and their domains of application.
The commentary primarily draws on the work of Kim et al. (2008) who examined the peer-reviewed literature on TP, from the publication of Goldratt’s It’s Not Luck in 1994 up until early 2006. Two prior studies, by Rahman (1998) and Mabin and Balderstone (2000; 2003), provided reviews of the broader TOC literature, and reviewed papers published before 2000. Kim et al.’s (2008) work complemented and extended those other reviews by focusing on TP up to early 2006. These reviews have provided a valuable summary, for academics and practitioners, of the developing TOC body of knowledge that have found outlet in the peer-reviewed literature. In addition, Watson et al.’s (2007) review of the evolution of TOC, while not attempting to provide a literature review, does discuss TP and identifies some deficiencies.
Whereas Rahman’s (1998) review of the TOC literature classified the TOC literature based on what he termed the philosophical orientation and application of TOC, the review conducted by Kim et al. (2008) used an extended set of five dimensions or orientations: theoretical or methodological, application, time,