Process Decision Program Chart (PDPC)

PDPC is like a tree diagram that seeks to identify all the things that can possibly go wrong and the necessary countermeasures to prevent or correct them. It has its roots in operations research and has been developed as a preventive and corrective tool in quality control and product and process design.

PDPC lists undesirable events and corresponding contingency measures. Its power lies not only in anticipating upcoming risk conditions but also in planning to respond adequately to such conditions. You should use it when you have serious concerns about the likelihood of adverse and unpredictable outcomes.

PDPC has no definite structural rules. Mizuno suggests the following guidelines:^[16]

• Start with the present.

• Suggest a possible solution under a conceivable future.

• Anticipate undesirable outcomes.

• Present a way to reach a better result.

• Decide on a course of action.

• Review the process in a flexible manner that accommodates new conditions.

PDPC is similar in appearance to the tree diagram, except that it is dynamic and characterized by flow lines chronologically (see Figure 7.6). The steps for constructing a PDPC are as follows:

1.	Form a team that represents the tasks involved.
2.	Present a basic solution to the problem in question. It can begin with the tree diagram of the process or product if available. Draw it on a flip chart or whiteboard.
3.	Discuss the challenges. These should be broad and should not only address current issues but also anticipate unforeseen issues and risks.
4.	Ask "What can possibly go wrong at this step?" and "What other paths might it take?", starting with the first step. Discuss each answer in terms of likelihood, risk implications, and countermeasures. Write them all down.
5.	Prioritize the issues and countermeasures. Consider them all together, because information related to one set of possibilities can influence another set.[17] Record all the problems and the countermeasures. Set a date for completing the process.
6.	Review and follow up on the due date.

Figure 7.6. A Process Decision Program Chart

PDPC is essentially a method to resolve system failures. But unlike the other well-known methods, such as Failure Modes and Effects Analysis and Fault Tree Analysis (see Chapter 13), PDPC can reveal not only logical phenomena but also those expressed in light of new ideas. Used in addition to these methods, PDPC enhances reliability markedly.^[18]