Page 231 - Lean six sigma demystified

Chapter 5 Redu C ing d efe C t S with Six Sigm a 209

ExErcisEs

1. Over the next week, read your local newspaper and clip all of the articles involv-
ing product or service failure and the high costs of poor quality.

2. Develop a control chart of the problem area.
• In small groups, have participants select one indicator for defects, time, or cost.
Using real or best-guess data, have participants graph the current performance
of the indicator.

3. Develop Pareto charts of the problem area to laser: focus the analysis.
Two or more Pareto charts are often necessary to find a specific problem to
solve. If the team doesn’t narrow the focus here, they will end up with a whale-
bone diagram in step 2. Reinforce the link between the control chart and the
Pareto charts.
• In small groups, have participants identify the main contributors to the problem
indicator of defects, time, or cost. Using real or best-guess data, have partici-
pants identify the biggest contributor to the problem (big bar on the Pareto
chart).
• If possible, have participants further stratify the biggest contributor or have
them identify how they would further focus the problem.
• Have participants use the Pareto chart to write a problem statement.

4. Purpose: Develop cause-and-effect diagram.
• In small groups, have participants select the type of diagram and the most likely
main contributor (big bone).
• have participants ask ‘why?’ up to five times to identify at least one root cause
of the problem.
• Have participants discuss how they would verify this root cause using data.

5. Develop countermeasures. During the analysis of the problem, obvious counter-

measures will often appear. The first three steps of the process tend to overlap.
In the first few minutes of the first meeting, members will often offer unvali-
dated countermeasures and root causes. These should be captured and stored
in the appropriate place in the improvement story.
Once the root causes have been validated with data to ensure that the team is
tackling the true origin of the problem, various alternative countermeasures can
be evaluated. There are two key questions.
• how effective is the countermeasure at preventing the root cause?
• How feasible (i.e., cost beneficial) is the countermeasure in terms of resources,
time, and cost to implement?
which countermeasures are the most effective and feasible? avoid implement-
ing too many at one time; one may cancel out another.