The Seven Basic Tools of Quality

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The Seven Basic Tools of Quality


These are the “must” list for SPC programs. Anyone installing and using an SPC program will use most of these seven tools.


1. Flowcharts– A pictorial (graphical) representation of the process flow – showing the process inputs, activities, and outputs in the order in which they occur.


2. Checksheets – A list of items inspected (checked). The list is usually organized in a standardized format designed to facilitate information gathering and, later, quantitative analysis. It also assures that different people will collect required information in the same way.


3. Histograms – A graphical summary of variation in a set of data. A pictorial means of organizing, summarizing, analyzing, and displaying data.


4. ParetoAnalysis – Uses a specially organized histogram (the Pareto chart) to provide a picture that instantly identifies those problem of greatest concern – those problems that should be addressed first.


5. Cause and effect diagram – As the name implies, this tool is just a tool of causes and effects diagrammed to show the interrelationships. The diagram is a form of tree diagram on its side so that it looks like a fishbone. It is also called Ishikawa diagram after the man who invented it.


6. Scatter diagram – Cartesian coordinate type (X,Y graphs) that illustrate cause and effect relationships between two types of data.


7. Control Charts – Graphs of one or more important characteristics of a product. They are statistical techniques to analyze the process, and to provide information for correction and improvement of the process, and thus the products produced on that process.

Seven new quality tools


1. Affinity diagrams – The affinity diagram is a visual tool that allows an individual or a team to group a large number of ideas, issues, observations or items into categories for further analysis. The tool groups the ideas in a way that allows those with natural relationships or relevance to be placed together in the same group or category.


2. Arrow Diagrams – The arrow diagram—also known as activity diagram, network diagram, activity chart, node diagram or critical path method chart—is used to illustrate the order of activities of a process or project. Makes use of program evaluation review technique (PERT) and the critical path method (CPM)


3. Matrix diagram – Analysis relations between two different factors. Also used in developing customer requirements into design requirements, then into vendor or purchasing requirements, and then into production requirements (In this form it is also called as Quality Function Deployment – QFD – Diagram)


4. Matrix Data analysis diagram – Applies quantitative analysis to the matrix diagram.


5. Process decision program chart (PDPC) – Used to guide the implementation process. It organizes each possible chain of events in a complex plan so that all possible events are identified and planned.  For instance, anything that can possibly can go wrong will be identified, and a plan, and resources, already formulated in case any of these problem occur.


6. Relations Diagram – (Also called the interrelationship diagram). Analyses the interrelationships of complex systems, i.e., which portions of the system relate to which other portions, and how and to what extent.


7. Tree Diagram – A tree diagram allows you to detail a conceptual or high level goal into more operational tasks to achieve the desired result. The tree diagram starts with one item that branch into two or more branches, each of which branches into two or more, and so on.


Reference used : Book ” Statistical Process Control” By Leonard A. Doty

ASQ Quality Progress Magazine April 2012 edition



The Seven Basic Tools of Quality is a designation given to a fixed set of graphical techniques identified as being most helpful in troubleshooting issues related to quality.[1] They are called basic because they are suitable for people with little formal training in statistics and because they can be used to solve the vast majority of quality-related issues.[2]

The seven tools are:[3][4][5]

The designation arose in postwar Japan, inspired by the seven famous weapons of Benkei.[6] It was possibly introduced by Kaoru Ishikawa who in turn was influenced by a series of lectures W. Edwards Deming had given to Japanese engineers and scientists in 1950.[7] At that time, companies that had set about training their workforces in statistical quality control found that the complexity of the subject intimidated the vast majority of their workers and scaled back training to focus primarily on simpler methods which suffice for most quality-related issues.[8]

The Seven Basic Tools stand in contrast to more advanced statistical methods such as survey sampling, acceptance sampling, statistical hypothesis testing, design of experiments, multivariate analysis, and various methods developed in the field of operations research.[9]

The Project Management Institute references the Seven Basic Tools in A Guide to the Project Management Body of Knowledge as an example of a set of general tools useful for planning or controlling project quality.[10]


See also


  1. Montgomery, Douglas (2005). Introduction to Statistical Quality Control. Hoboken, New Jersey: John Wiley & Sons, Inc. p. 148. ISBN 978-0-471-65631-9. OCLC 56729567.
  2. Ishikawa, Kaoru (1985), What Is Total Quality Control? The Japanese Way (1 ed.), Englewood Cliffs, New Jersey: Prentice-Hall, p. 198, ISBN 978-0-13-952433-2, OCLC 11467749, “From my past experience as much as ninetey-five percent of all problems within a company can be solved by means of these tools.”
  3. Nancy R. Tague (2004). “Seven Basic Quality Tools”. The Quality Toolbox. Milwaukee, Wisconsin: American Society for Quality. p. 15. Retrieved 2010-02-05.
  4. Ishikawa, Kaoru (1985), What Is Total Quality Control? The Japanese Way (1 ed.), Englewood Cliffs, New Jersey: Prentice-Hall, p. 198, ISBN 978-0-13-952433-2, OCLC 11467749, “Elementary Statistical Method (the so-called Seven Tools) 1. Pareto chart: The principle of vital few; trivial many 2. Cause and effect diagram (This is not precisely a statistical technique) 3. Stratification 4. Check sheet 5. Histogram. 6. Scatter diagram (analysis of correlation through determination of median; in some instances, use of binomial probability paper) 7. Graph and control chart (Shewhart control chart)”
  5. Imai, Masaaki (1986), Kaizen (Ky’zen), the Key to Japan’s Competitive Success (1 ed.), New York: Random House, pp. 239–240, ISBN 9780394551869, OCLC 13010323, “The seven statistical tools used for such analytical problem-solving are: 1. Pareto diagrams […] 2. Cause-and-effect diagrams […] 3. Histograms […] 4. Control charts […] 5. Scatter diagrams […] 6. Graphs […] 7. Checksheets.”
  6. Ishikawa, Kaoru (1990), Introduction to Quality Control (1 ed.), Tokyo: 3A Corp, p. 98, ISBN 978-4-906224-61-6, OCLC 23372992, “They were named the Seven QC Tools after the famous seven weapons of the Japanese Kamakura-era warrior-priest Benkei which enabled Benkei to triumph in battle; so too, the Seven QC Tools, if used skillfully, will enable 95% of workplace problems to be solved. In other words, intermediate and advanced statistical tools are needed in about only 5% of cases.”
  7. “The seven basic tools of quality”. London: Improvement and 2007-11-30. Retrieved 2013-05-18. “Ishikawa had a desire to ‘democratise quality’: that is to say, he wanted to make quality control comprehensible to all workers, and inspired by Deming’s lectures, he formalised the Seven Basic Tools of Quality Control.”
  8. Ishikawa, Kaoru (1985), What Is Total Quality Control? The Japanese Way (1 ed.), Englewood Cliffs, New Jersey: Prentice-Hall, p. 18, ISBN 978-0-13-952433-2, OCLC 11467749, “It is true that statistical methods are effective, but we overemphasized their importance. As a result, people either feared or disliked quality control as something very difficult. We overeducated people by giving them sophisticated methods where, at that stage, simple methods would have sufficed.”
  9. Ishikawa, Kaoru (1985), What Is Total Quality Control? The Japanese Way (1 ed.), Englewood Cliffs, New Jersey: Prentice-Hall, pp. 198–9, ISBN 978-0-13-952433-2, OCLC 11467749, “I divide statistical methods into the following three categories according to their level of difficulty. 1. Elementary Statistical Method (the so-called Seven Tools) […] 2. Intermediate Statistical Method […] 3. Advanced Statistical Method (using computers concurrently)”
  10. A Guide to the Project Management Body of Knowledge. Newtown Square, PA: Project Management Institute. 2013. pp. 236–238. ISBN 978-1-935589-67-9.



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