Performance assessment, program sustainability

Quality control consists of sustaining the level of performance or quality as assessed over a. selected time period. The explanation of the concepts of quality control is often based on an industrial production process in which the quality can be or has been assessed by independent evidence perhaps of a specialized and more costly nature than the control testing that is to be established. Thus the state of statistical control as defined below is guaranteed by this independent evidence. Once this is in place, the operations to set up a control operation are straightforward. However in a laboratory setting independent evidence for a state of control may or may not be available. When it is not available, the process of establishing a bona fide quality control program must proceed by an iteration process. 

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