Local actions and action on the system

Simple statistical process control techniques can detect special causes of variation.Discovering a special cause of variation and taking proper action is usually the responsibility of someone who is directly connected with the operation.Although management must sometimes be involved to correct the condition,the resolution of special cause of variation usually requires Local Action .This is especially true during the early process improvement efforts.As one succeeds in taking the proper action on special causes,those that remain will often require management action,rather than local action.

These same simple statistical techniques can also indicate the extent of common causes of variation,but the causes themselves need more detailed analysis to isolate.
The correction of these common causes of variation is usually the responsibility of management.Sometimes people directly connected with the operation will be in a better position to identify them and pass them on to management for action.Overall,though,the resolution of common causes of variation usually requires action on the system.

Only a relatively small proportion of excessive process variation-industrial experience suggests about 15%-is correctable locally by people directly connected with the operation.The majority-the other 85%-is correctable only by management action on the system.

Confusion about the type of action to take is very costly to the organization,in terms of wasted effort,delayed resolution of trouble,and aggravated problems.It may be wrong,for example,to take local action (e.g., adjusting a machine)when management action on the system is required (e.g., selecting suppliers that provide consistent input materials).