7 QC Tools/ The Six Sigma Tools

There are seven basic quality improvement tools [7 QC Tools] that are used by Quality Circle teams, and are fundamental to the Total Quality Management, Total Quality Control, Lean, and Six Sigma initiatives.

• 1. Check sheet: A form to collect and tally data for further analysis.
• 2. Fishbone (Ishakawa) diagram: Fishbone diagrams are used to drill down to find the root cause of a problem. As the name implies, the diagram looks like the bones of a fish, where each main bone represents a specific category of possible root cause, and the subsequent drilling down is shown as smaller and smaller bones.
• 3. Histogram: This is a bar graph showing the frequency of a set of data, usually continuous data. The histogram allows you to see the centre of the data, the range of the data, and the distribution of the data. It is a very useful snapshot. The downside is that you can't see the sequence or order of the data.
• 4. Pareto chart: This chart is based on the 80/20 principle that says 80% of your effect is caused by 20% of your causes. For example, 80% of your sales comes from 20% of your customers. Dr. Joseph Juran, who developed this chart, often referred to this principle as the vital few and trivial many. He later revised that to the vital few and useful many. The Pareto chart lists the causes in descending order of frequency or magnitude. It is used to prioritize what you should look at first to improve your process.
• 5. Control chart: A control chart is a statistical tool that looks at your process data over time for the purpose of distinguishing between special cause and common cause variation.
• 6. Scatter diagram: These are also known as scatter plots. They're used to show a graphical correlation between a set of paired data on an X and Y axis. It is the graphical representation of what you would use for regression analysis.
• 7. Stratification: This is a graph that shows data that has been stratified when the data comes from different sources. It is useful to view the data by certain strata such as shift, gender, geographic location, machines, or suppliers.

Benefits of the 7 QC tools

These seven tools are easy to understand and apply and will help you understand what is going on in your process.

Easy

These 7 QC tools are easy to understand and implement yet powerful in identifying root causes, in discriminating between types of variation, and as a visual description of your data. A picture is truly worth 10,000 words (or statistical calculations).

Software-driven

Gone are the days when you had to draw all your graphs by hand. There are many simple and cost-effective software packages that will take your data and quickly produce graphs.

80/20

The Pareto principle applies to the 7 QC tools as well. 80% of your quality issues can be addressed by using 20% of the most common tools.