**3. Data evaluation**

Metrology and inspection together serve as the control function of the quality of conformance. Inspection helps to evaluate the degree of conformance or nonconformance to specifications, provides for reporting of deficiencies early in the production process, and helps to assure that desired quality requirements have been met. The field of knowledge concerned with measurement. Metrology includes all aspects of both theoretical and practical with reference to measurements, whatever their level of accuracy, and in whatever fields of science or technology they occur. Since quality performance decisions are based on inspection and measurement, undesirable consequences may result if these tasks are not performed properly. Not only incorrect measurements lead to wrong decisions, which can have serious consequences, but also improper data evaluations can cause undesirable consequences. Since Statistical Process Control is the utilization of statisti-

**Figure 1.** Hierarchy of calibration/traceability pyramid.

cal tools and methods to acquisite and to analyze data in order to monitor process capabilities, it is widely used in data evaluation. Quality control charts and the other statistical tools are used to analyze processes enabling appropriate actions to achieve improved or stabilized processes. They help to ensure that the process operates efficiently and allow organizations to understand variation in their processes, differentiating common causes from special or assignable causes of variation.
