Where Does Statistical Process Control Fit into Six Sigma DMAIC?
Six Sigma was born in an organization that practiced Statistical Process Control as an ongoing management technique. At Motorola inputs and outputs from most processes were monitored using control charts, and capability studies and indices were used to assess quality. The same is, unfortunately, not true in many of the organizations that have tried implementing Six Sigma in the 22 years since Motorola’s launch of its quality improvement program. As a result, the kind of rigor around data-based management that was taken for granted at Motorola has often been side-tracked and has led to a lack of emphasis on Statistical Process Control. In many organizations’ Six Sigma DMAIC project flows, Statistical Process Control may not be mentioned at all. Control charts are part of the Control Phase in Six Sigma DMAIC, but not used in other phases. Wheeler1 suggested this as one of the flaws in most Six Sigma DMAIC approaches: The failure to investigate what can be accomplished by operating the pr
