Page 227 - DMGT524_TOTAL_QUALITY_MANAGEMENT

Total Quality Management

Notes 14.5.6 Classification of Factors

Tools like brainstorming and cause & effect diagrams helps in identification of factors and
preparing a complete list of the factors involved in any experiment. Factors listed can be classified
into three categories:
Experimental Factors
Control Factors
Error or Noise Factors
1. Experimental factors are those which we really experiment with by varying them at various
levels.
2. Control Factors are those which are kept at a constant (controlled) level throughout
experimentation.
3. Error or Noise factors are those which can neither be changed at our will nor can be fixed at
one particular level. Effect of these factors causes the error component in the experiment
and as such these factors are termed as error or noise factors.

14.5.7 Response and Type of Model for Analysis

The ultimate observations or data generated by the experiment is known as the response. The
response may be:

Continuous or measurement type and follows a normal distribution
Continuous or measurement type but does not follow normal distribution

Self Assessment

Fill in the blanks:
14. …………………… is a discipline that has very broad application across all the natural and
social sciences.
15. The …………………… to product and process optimization is to conduct one variable
at-a-time experiments.

14.6 Statistical Fundamentals

Statistical Process Control (SPC) or Statistical Quality Control (SQC) is the main area covered
under statistical tools for quality. This area includes the following techniques:
1. Control Charts
(a) Control charts for variables

(b) Control charts for attributes
2. Sampling Inspection
Control charts are aimed at process control. Use of control charts ensures that the process
continues to work with its natural capability and any significant variation in the process is
promptly detected and corrected. Scientific sampling ensures that amount of inspection is reduced
while agreed upon quality levels are adhered to. Sampling inspection can be applied to only
those products which have been produced with a controlled process.

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