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.