Top Page | Upper Page | Contents | About This Site | JAPANESE

Seven QC Tools and New Seven QC Tools

Useful tools are collected in TQC , to widen the activity of SPC . Those are called "seven QC tools" and "new seven QC tools". Those tools are beginners of QC activity.

Seven QC Tools

Statistical approach and visual approach are key-points. Graphs are important.

"Seven QC tools" is also called "Q7"

Some people say that "control chart" is one of the "graph" and stratified sampling is one of the seven QC tools.

• Pareto Chart : Combination of bar chart and accumulation distribution chart
• Histogram : for 1-dimension data
• Graph : Bar chart, line chart, pie chart, etc.
• Dot Plot (Scatter Diagram) : for 2-dimension data. To check the relationship of two characteristics
• Fishbone diagram (Cause-and-Effect Diagram) : Systematic diagram of cause and effect.
• Check Sheet : A list of check points.
• Control Chart : A kind of line chart. X-dimention is time. To check the stability of the movement of data.

New Seven QC Tools

New seven QC tools are made to analyze non-quantity information (knowledge) mainly. Those tools are could be said as reasoning methods.

"New seven QC tools" is also called "N7"

• Affinity Diagram : Grouping of the idea of Brainstorming
• Association Diagram : Diagram of Why-why analysis. It is good to use if cause-and-effect contains circulation structure
• Tree Diagram : Collection of plans and methods systematically.
• Matrix Diagram : A matrix to express the strongness of relationship between two things. Basic of QFD (Quality Function Deployment)
• Arrow Diagram : Same to PERT
• Process Decision Program Chart (PDPC) : Same to "Flow chart"
• Matrix Data Analysis : Same to Principal Component Analysis

Weakness of Q7 and N7

Most of Q7 are tools for quantity data analysis. But Check-Sheet and Cause-and-Effect Diagram are for knowledge analysis.

Most of N7 are tools of knowledge analysis. But Matrix-Data-Analysis is for quantity data analysis. And it is mathematically too difficult to study for beginners.

From other viewpoint, Q7 and N7 are not only for Quality Study today because they are introduced as useful tools for various business use. So the name, "QC", is not suitable.

I tried to arrange " Tools of Data Science (G7, W7, M7) " to improve these problems.

NEXT Tools of Data Science (G7, W7, M7)