Theory of Constraints Handbook - James Cox Iii [438]
Developments Pertaining to the Building and Presentation of the CRT The CCRT is a stripped-down CRT that facilitates communication with managers. It also serves to enhance buy-in by starting from a positive proposition (the desired objective, box A in the EC) rather than just a negative one (the core problem), and shows the relationship between these and the observed UDEs (Scheinkopf, 1999, Chapter 12; Houle and Burton-Houle, 1998; Button, 1999). Button also presents Goldratt’s three-cloud approach for building a CRT, which was developed to reduce the time and difficulty of building a CRT. The traditional approach incorporates a 10-step procedure seeking likely causes for observed UDEs. The 3-UDE EC approach uses four steps to construct a CRT: (1) identify a list of UDEs; (2) generate three ECs (from seemingly unrelated problems) from the list of UDEs; (3) construct a GEC from the three ECs, thus identifying the likely core conflict; and (4) build a CRT that starts with the core conflict and harnesses the logic and pictorial representation of the GEC. While Dettmer (2007) decries such an approach, it is recommended in other texts (Cox et al., 2003), and the Kim et al. (2008) review reveals that both approaches have been much in use. Dettmer instead prefers the IO map as the starting point for TP analysis, arguing that the core conflict is more likely to be identified by the IO map’s more strategic approach to identification of UDEs. There may also be occasions when three clouds may not lend themselves to a GEC when one EC is nested or embedded in the other EC (Davies and Mabin, 2009). The Strategy and Tactics (S&T) trees—covered in Chapter 25—were not evident in the review of the peer-reviewed literature, but are being used increasingly by TOC developers and practitioners.
TABLE 23-1 TP Tools—Reported Usage—1994 to 2009
TABLE 23-2 Classification of the Literature by TP Tools-in-Use—1994 to 2009
Methods Being Used Singly or in Sequenced Use Once TOC practitioners have identified What to Change by using the CRT, the second step in the traditional TP approach deals with the search for a plausible solution to the root cause; that is, to What to Change. This task can be accomplished with the aid of the EC and the FRT (see, for example, Taylor and Thomas, 2008; Taylor and Poyner, 2008). As evident from Table 23-2, many authors have seen the advantage of the EC as a standalone tool or method, and how it can lead to a win-win solution by surfacing and breaking the assumptions underlying the supposed conflict. The papers reviewed by Kim et al. (2008) described use of the EC method in conflict situations as varied as interpersonal conflict between sales manager and salesperson, writing MIS mini-cases, the creative design process, SCM, resource allocation in schools, TOC education, forest harvesting, Lean manufacturing and TOC implementation, managerial dilemmas, and “traditional” measurement. (See Kim et al., 2008 for further details.)
Nevertheless, it has also been suggested that the use of the EC following development of the traditional CRT provides potentially far more diagnostic and solution generation power than individual use of the EC or CRT. One reason is that once a core problem has been identified using a CRT, it is more likely that a solution can be developed using the EC. Several papers (see Moura, 1999; Smith and Pretorius, 2003; Choe and Herman, 2004; Umble et al., 2006) describe and explain the combined use of both TP tools to identify the system’s core problem and possible solution.
CRT-EC-FRT Method and EC-CRT(B)-FRT(B)-NBR Method Other variants on the “traditional” approach (CRT-EC-FRT) include the GEC-CRB-FRB-NBR multi-method approach, a refinement using the Current Reality Branch (CRB) and Future Reality Branch (FRB) (Cox et al., 2003). Cox et al. (2005) suggest using the EC rotated clockwise to provide a skeletal