AAOM Handbook

identified in the KPI capability histogram. A target should therefore include a specification, a required confidence level (the percentage of results that must meet the specification) and the interval over which the confidence must be met. In the following example, simulating the results of a product batching process; • 87% of the batches produced lie between the specification limits, ie the confidence level is 87%, and • the mean weight of the batches produced by the process is 98kg, and the mean weight of the batches that meet the specification limits is 100kg.

The measures of Process outcomes are typically of a lagging nature. Consequently, it may be hours, days, months or years between the time a change to the input, operation, or servicing of the Process is made, and the results of that change become evident in some of the outcome measures. Once such a lagging change has been initiated it cannot be reversed instantly. There will also be a time lag to reverse the change, during which the resulting variation in output is causing waste. Hence, while it is important to measure the output of the Process we cannot avoid the risk of variation in it if that is all we measure. In order to deliver the output of a Process there must be an understanding of its underlying theory, and the technical standards and guidelines applying to it. These will help define the Production and Service work. An example is the blasting of rock in a mine. The purpose of the blasting is to deliver fragmented rock. The underlying theory is that drilling a particular pattern of holes, filling them with the specified type and amount of materials, and firing the holes in a specified sequence, will produce the correct size and quantity of rock fragments, in the right position. This could be summarised by stating that if you do the right work, at the right time, and in the right way, you will get the right outcomes. A more common example of this theory in action can be observed with the warranty provisions applied to cars. The warranty is only