Six Sigma Black Belt | Business Process Management | Lesson Summary Example: Data Analysis Tools
Data Analysis Tools
Tool Description When to Use Histograms According to The Quality Toolbox
by Nancy R. Tague, "A frequency distribution shows how often each different value in a set of data occurs. A histogram is the most commonly used graph to show frequency distributions."
• When the data are numerical.
• When you want to see the shape of the data’s
distribution, especially when determining whether the output of a process is distributed approximately normally.
• When analyzing whether a
process can meet the customer’s requirements.
• When analyzing what the
output from a supplier’s process looks like.
• When seeing whether a
process change has occurred from one time period to another.
• When determining whether the outputs of two or more processes are different.
• when you wish to
communicate the
distribution of data quickly and easily to others.
Line Graphs According to The Quality Toolbox by Nancy R. Tague, "A line
graph is the simplest kind of
graph for showing how one variable, measured on the vertical y-axis, changes as another variable, on the horizontal x-axis, increases. The data points are connected with a line. The x-axis variable is called the dependent variable, because its value depends on the value of the independent variable."
• When the pairs of data are
numerical
• When you want to show
how one variable changes with another, continuous variable, usually time.
• Only when each independent
variable is paired with only one dependent variable.
Data Analysis Tools
Six Sigma Black Belt | Business Process Management | Lesson Summary Example: Data Analysis Tools
172 affected by special causes of variation)."
• When determining whether
your quality improvement project should aim to prevent specific problems or to make fundamental changes to the process.
Pareto Analysis According to The Quality Toolbox by Nancy R. Tague, "A Pareto
chart is a bar graph. The lengths
of the bars represent frequency or cost (time or money), and are arranged with longest bars on the left and the shortest to the right. In this way the chart visually depicts which situations are more significant."
• When analyzing data about
the frequency of problems or causes in a process.
• When there are many
problems or causes and you want to focus on the most significant.
• When analyzing broad
causes by looking at their specific components.
• When communicating with
others about your data.
Affinity Diagram According to The Quality Toolbox by Nancy R. Tague, "The affinity
diagram organizes a large
number of ideas into their natural relationships. This method taps a team’s creativity and intuition. It was created in the 1960s by Japanese anthropologist Jiro Kawakita."
• When you are confronted with many facts or ideas in apparent chaos
• When issues seem too large and complex to grasp
• When group consensus is necessary
Nominal Group Technique According to The Quality Toolbox by Nancy R. Tague, "Nominal
group technique (NGT) is a
structured method for group brainstorming that encourages contributions from everyone. "
• When some group members are much more vocal than others.
• When some group members think better in silence.
• When there is concern about
some members not participating.
• When the group does not
easily generate quantities of ideas.
• When all or some group
members are new to the team.
• When the issue is
controversial or there is heated conflict.
Matrix Diagrams According to The Quality Toolbox by Nancy R. Tague, "The matrix
diagram shows the relationship
between two, three or four groups of information. It also can give information about the
relationship, such as its strength, the roles played by various individuals or measurements."
• An L-shaped matrix relates two groups of items to each other (or one group to itself).
• A T-shaped matrix relates three groups of items: groups B and C are each related to A. Groups B and C are not related to each other.
• A Y-shaped matrix relates
three groups of items. Each group is related to the other two in a circular fashion.
• A C-shaped matrix relates
Data Analysis Tools
Six Sigma Black Belt | Business Process Management | Lesson Summary Example: Data Analysis Tools
together simultaneously, in 3-D.
• An X-shaped matrix relates four groups of items. Each group is related to two others in a circular fashion.
• A roof-shaped matrix relates
one group of items to itself. It is usually used along with an L- or T-shaped matrix.
Prioritization Matrix A prioritization matrix is a decision making tool using a systematic process to narrow choices. It is a variation of an L-shaped matrix (discussed in Matrix Diagrams). A
prioritization matrix allows raters to rank the options against pre-determined scales, weights and criteria to determine order of importance.
• When prioritizing the variables with the greatest significance.
• When reaching consensus in small teams.
• When comparing a few options to specific standards.
• When narrowing a list of
options to one choice.
• When making decisions
based on multiple criteria (best when used for six to eight criteria).
• When selecting one product,
approach, supplier, option or problem.
Metrics Summarized
Six Sigma Black Belt | Business Process Management | Lesson Summary Example: Metrics Summarized
174
Metric Formula
Defects per Unit (DPU) DPU = Defects / Units Parts per Million (PPM) PPM = DPU x 1,000,000 Defects per Million
Opportunities (DPMO)
Rolled Throughput Yield (RTY) RTY = N (units entering process) – (# of reworks + # in scrap) / N (units entering process) Return on Assets (ROA) ROA = Net Income/Total
Assets Return on Investment (ROI) ROI = Net
Income/Investment Net Present Value (NPV)
DPMO = (Defects/Total Opportunities) x 1,000,000 OR DPMO = DPO x 106
Lesson Bibliography
Six Sigma Black Belt | Business Process Management Concept: Lesson Bibliography
American Society for Quality. ASQ’s Foundations in Quality Learning Series: Certified Quality Engineer. Milwaukee, WI: ASQ, 2000.
American Society for Quality. Six Sigma Green Belt Certification Preparation Course, Version 1 (web-based course). Milwaukee, WI, 2006.
ASQ Statistics Division. Rudy Kittlitz, editor. Glossary and Tables for Statistical Quality Control. 4thed. Milwaukee, WI: ASQ Quality Press, 2005.
Benbow, Donald and T.M. Kubiak. The Certified Six Sigma Black Belt Handbook. Milwaukee, WI: ASQ Quality Press, 2005.
Breyfogle, Forrest W. III. Implementing Six Sigma: Smarter Solutions®Using
Statistical Methods. 2nded. Hoboken, NJ: John Wiley and Sons, Inc., 2003.
Camp, Robert C. Benchmarking: The Search For Industry Best Practices That Lead to Superior Performance. Milwaukee, WI: ASQ Quality Press, 1989.
Keller, Paul. Six Sigma Demystified. New York, NY: McGraw-Hill, 2005.
Pries, Kim H.Six Sigma for the Next Millennium: A CSSBB Guidebook. Milwaukee, WI: ASQ Quality Press, 2006.
Pyzdek, Thomas. The Six Sigma Handbook: A Complete Guide for Green Belts, Black Belts, and Managers at All Levels, Revised and Expanded, 2nded. New York:
McGraw-Hill, 2003.
Tague, Nancy R. The Quality Toolbox. 2nded. Milwaukee, WI: ASQ Quality Press,