The Psychology of Quality and More

A Toolbook for Quality Improvement and Problem Solving (contents)

Process Decision Program Chart (PDPC): How to understand it

The Quality Toolbook > Process Decision Program Chart (PDPC) > How to understand it

When to use it | How to understand it | Example | How to do it | Practical variations

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How to understand it

Any plan is a statement of what is expected to happen, although as many planners will agree, the best laid plans of mice and men seldom happen exactly as expected. There are two approaches to coping with this problem: firefighting or risk management.

Firefighting is an approach that is taken surprisingly often. The manager spends most of his or her time coping with the unexpected, issuing orders, changing plans and slipping schedules. It can give a false sense of heroism as immediate dangers are averted by dramatic last-minute actions.

On the other hand, risk management involves looking ahead at the planning stage for potential future problems. The most difficult part of this activity is often the actual identification of risks. The Process Decision Program Chart (commonly abbreviated to the less unwieldy PDPC) provides a simple method to help in identifying both risks and countermeasures.

Quite simply, if the plan is displayed diagrammatically (typically in a Tree Diagram), then identified risks and countermeasures are added in subsequent boxes, as Fig. 1. below. This may appear to be quite trivial, but as with many other tools, the construction and thought involved is as important as the final diagram.

Fig. 1. From Plan to risks and countermeasures

The simplicity and flexibility of the PDPC can result in very different diagrams, with various levels of detail and different symbols and boxes used to indicate specific items. The common theme is the identification of risk and how it might be handled.

Two of the most common elements of risk are cost and time, for example where there is a risk in a busy schedule of key equipment being unavailable and consequent time loss and additional expense being incurred in hiring replacement machines. A possible resolution of this risk is to hire standby equipment, which may be selected if this cost is considered to be lower than the cost of missing a committed completion date.

There are three possible routes that may be taken for coping with identified risks: risk avoidance, risk reduction and contingency planning. The chosen approach in each case may affect actions during the construction of the PDPC, as indicated in the diagram below.

Risk avoidance means not taking an action that will result in an identified risk. Typically this route involves finding alternative actions. In sensitive cases, where the consequences of the risk occurring are be catastrophic and there is no acceptable alternative, risk avoidance could result in the whole plan being abandoned.

Risk reduction means taking some action that will reduce, but not eliminate, the identified risk. It may involve additional actions, such as extra testing to reduce the risk of failure of the final product. Typically this results in a trade-off of additional cost against reduced risk.

Contingency planning does not reduce the chance of the identified risk occurring. Instead, it involves making additional plans, so that if the risk does occur you will be prepared and able to control the situation with the minimum cost and disruption.

Fig. 2. Risk activities

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