Six Sigma is a powerfully effective methodology for quality improvement – no matter the industry or vertical. Here are four of the most important of the Six Sigma statistical tools:
Control Charts
One of the fundamental tools of Six Sigma’s process improvement methodology is the control chart. Control charts have two basic uses in an improvement project. The first and most common application is to monitor process stability and control. The second, and not quite as common, is using it as an analysis tool.
The control chart is responsible for monitoring the variation of key characteristics and providing diagnostic data about process capability. This data will then be used to analyze variation in process data to uncover any process defects. Once statistical formulas have been applied to the data gathered from the process, the control chart’s upper and lower control limits are calculated. Data points that fall outside of this range represent the process variations that are caused by irregularities and can be identified and eventually eliminated. These charts are highly effective in preventing future defects and they help ensure process consistency. Using this tool, an organization can monitor, control, and improve processes over time in a precise manner, which lowers costs and improves efficiencies.
FMEA
Failure Modes and Effects Analysis (FMEA) is a comprehensive tool that helps organizations identify and eliminate weak points in the early conception stages of any product or process. FMEA allows Six Sigma teams to identify potential failure modes within any industry that have been caused by either design or process deficiencies. In this way, FMEA improves the quality of processes, services and products by preventing problems before they occur. It is also able to track and document actions that were taken in an effort to reduce risk while integrating with the DMAIC methodology.
Histogram
Histograms are created by dividing the range of data into equally-sized segments. This visual tool makes it easier for teams to quickly answer a few critical questions, namely: what distribution does the data have? What is the most common system response? Is the data symmetric or does it contain outliers?
Pareto Chart
Graphing can be a major component of any process improvement. The Pareto chart graphically summarizes the relative importance of the differences between groups of data. Dividing the range of data into groups, the vertical axis represents the cumulative percentage while the horizontal axis represents the groups of response variables.
The Pareto chart differs from the histogram in that it is ordered in descending frequency magnitude. This tool allows Six Sigma teams to focus their efforts on identifying the largest issues facing the process, and by doing so, will help facilitate the greatest improvements. In essence, this one tool can help organizations uncover the 20% of sources that cause 80% of problems.
While this is not an exhaustive list of Six Sigma tools, it does highlight some of the most critical ones organizations may use to improve products, services and processes. Visit our Six Sigma Glossary here.
