4.2 Variant II
The second variant of the methodology for the realization of the problem-solving process in
the frame of SPC (Fig. 6.) has been designed for the processes with low dynamics but with
larger number factors influencing the analyzed quality characteristics. It evokes additional
activities within the preparatory phase. From all factors (causes) defined in Ishikawa
diagram the most probable causes must be selected by score and then the most important
causes must be chosen using for instance Pareto analysis. Some quantitative indicator then
should be assign to every important cause. The check sheet for recording values of these
indicators should be then designed to be possible to explicitly assign these values to rational
subgroups of the analyzed quality characteristic values. In OCAP corrective or
improvement actions will be bound to these indicators. It means that both values of
controlled quality characteristic and values of indicators mentioned above must be collected
and recorded. When control chart signalizes non-stability the analysis of these indicators
must be realized in order to be able to identify particular cause of non-stability.
The next steps of the problem-solving process are the same as in variant I except the
situation when the SPC has not resulted in the variability reduction. Then the selection and
the analysis of the indicators could be repeated.
4.3 Variant III
The third variant of the methodology (Fig. 7.) represents expansion of the second one to the
processes with both larger number of factors influencing controlled quality characteristic
and large process dynamics. The preparatory steps must be added with the analysis of time
leg in assignable causes treatment.