Statistical process control smoothing

The smooth operation flow of materials and products are further enhanced by Lean Sigma methodology where the variances within processes and between workstations are minimized by the statistical techniques of Statistical Process Control (see Basu, 2004, pp. 151-157). 

In the approach based on the analysis of historical data, no experiments are performed in retrospective validation, but instead all available historical data concerning a number of batches are combined and jointly analyzed. If production is proceeding smoothly during the period preceding validation, the data from in-process inspection and final testing of the product are combined and treated statistically. The results, including the outcome of process capability studies, trend analysis, etc., will indicate whether the process is under control or not... 

Table 1.3 provides an overview of chemometric methods. The main emphasis is on statistical-mathematical methods. Random data are characterized and tested by the descriptive and inference methods of statistics, respectively. Their importance increases in connection with the aims of quality control and quality assurance. Signal processing is carried out by means of algorithms for smoothing, filtering, derivation, and integration. Transformation methods such as the Fourier or Hadamard transformations also belong in this area. 

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