Page 200 - Six Sigma Demystified

180 Six SigMa DemystifieD

• Because the cost had been diverted away from the higher cost sales depart-
ment, control charting of the processing time was not instituted. The actual
processing time was less a concern, especially with the observed reduction
in process errors.
Per company policy, the cost savings would be estimated at the six month point,
and annually for three years thereafter.
The Order Fulfillment department was trained in the use of the new system.

Measure bottom-line Impact

A key part of the control stage is to continuously monitor the effects of the
process improvement. This is a critical part of DMAIC that often was neglected
in past improvement strategies.
The control plan should contain provisions for monitoring the process out-
put either as a method of control or as a sampling audit. Generally, the process
owner (operational personnel) will be responsible for ongoing tracking of the
applicable performance metric. This activity should continue for as long as
necessary, as often as necessary, to establish the underlying process capability.
Often sampling is fairly frequent in the beginning and tapers off once the pro-
cess has proven stable and capable of achieving the requirements. See the “Sta-
tistical Process Control Charts” section in Part 3 for a general discussion of
sampling frequency and the sample sizes necessary to detect process shifts.
As part of this control stage, a black belt will assume responsibility for verifying
the operational-level controls done by the process owners. In addition, the black
belt will audit the process on a regular (e.g., monthly) basis for the first year. The

audit should include observation of process procedures and controls, as well as
sampling or reviewing of the results of data samples to ensure process capability.
If the process exhibits any out-of-control behavior, the black belt should be
notified so that a further review can be made to identify its source. In such a
case, the process control should be investigated and perhaps tightened to reduce
the occurrence of further process instability. In cases of continued instability,
the process should be evaluated for a new Six Sigma project, with a critical
review of the initial Six Sigma project report for indication of its failings.
Just as crucial as process control is the ongoing tracking of the financial ben-
efits, usually on a monthly basis, as part of cost accounting reports. The financial
reporting must include actual expenditures and savings for each of the items
used for project justification in the define stage, as well as expenditures related