Process Control Issues

A number of questions come to mind when using quantitative measurement tools:

• What part of the process should be examined? Before, during or after an operation? In other words, the inputs, the process itself or the outputs? Maybe all three parts need to be measured. Moreover, any operational process usually has different stages to the process itself. For example, making whisky involves soaking the barley, initial fermentation, smoking the barley over a peat fire, mashing it, more fermentation, distillation, maturation and storage. So at what stage of the actual process should quantitative checks be made?

• When should the process be examined? For example, whisky needs to be matured over a number of years in oak casks or something similar. How often should sample checks be made?

• How many products should be checked? All of them, or just a sample? It would be time-consuming and costly to check all mass-produced consumer items. But, particularly where health and safety considerations are paramount, the more you can check the better, as the following example demonstrates. It is about how using a new 100 per cent screening model for retesting smears for possible cancerous cells produced significantly better detection rates than a...