Breviary Technical Ceramics






10.6 Quality

10.6.1 Statistical Assessment – Summary

The following methods of representation provide support for the adequate analysis of data from production and for problem-solving:

To distinguish partial problems according to their importance, errors logged by priority can be displayed using tally charts or histograms (Pareto diagrams/ABC analysis).

Listing possible causes of errors and organising them with respect to the influence of man, method, machine and material in order to determine their reasons and effects is generally represented on a herring-bone diagram (Ishikawa).

The conversion of series of measurements into distribution functions and their characteristic values (median x, variance ?) describe an operation and allow subsequent measurements to be predicted (histogram).

Control cards
The graphical representation of measurement data with respect to time along with the corresponding boundary values provides assistance to the decisions required for process control.

Scatter plots
The representation of individual values related by two influencing factors leads to a description of their relationships.

Diagram types
When analysing data, a clear graphical representation is helpful. In general, line plots, histograms and pie charts are used.

Test forms
These serve to represent the results of routine tests in tabular form.

Figure 232: Shapes of distributions and normal distribution.


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