Page 352 - Six Sigma Demystified
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332 Six SigMa DemystifieD
Figure F.32 Example of a process map showing stakeholder departments as swim lanes.
Interpretation
A quick review of the as-is process usually can uncover complexities in the
form of an excessive number of decision points and branches that may contrib-
ute to delays or even defects. When used to document the future (desired)
process, we strive to make process flow uncomplicated, with the fewest sym-
bols (tasks) and branches possible. This lack of complexity in the process will
tend to reduce the number of errors.
Process Performance indices
Process performance indices attempt to answer the question, Does this sample
meet customer requirements? It differs from process capability in that process
performance applies only to a specific batch of material. Samples from the batch
may need to be quite large to be representative of the variation in the batch.
When to Use
Process performance indices should be used only when SPC cannot be evalu-
ated or achieved. For example, we may have insufficient data to analyze SPC
