What Are The Seven Quality Measurement Tools?


 The seven quality tools are graphic techniques that accurately explain problems related to product quality and fix them. The seven quality control tools aim to solve about 95% of problems related to products or services. Therefore, to sustain any business, the quality of the product or service provided must be taken into account.

The quality of the product greatly affects the desired growth of the business, because the labor market today is very focused on the customer and seeks to provide the best customer experience. Therefore, effective quality management is one of the main factors that guarantee customer satisfaction.

table of contents:

The seven main quality control tools and their importance

The concept of the seven quality measurement tools was first developed by Kaoru Ishikawa, a professor of engineering at the University of Tokyo. The seven quality measurement tools are also known as Basic Quality Tools and the Seven QC Tools for short. There are various quality control tools, but the most prominent and most popular are these seven:

1. Chart

Graphs are used to measure one thing against another. A graph is a histogram or chart of different columns. These columns represent the average distribution and show the data. If the graph is normal, the graph takes the shape of a bell curve, and if it is abnormal, it takes different shapes according to the distribution. A chart is used Graph to summarize big data, compare measurements and specifications, and aid in decision-making.

Chart benefits

It shows the frequency distribution of values ​​or data and helps to evaluate the process and understand the variance. It also helps to understand the spread or variation of the data, its location, and shape, and to know whether the process is stable and predictable or not, to ensure that the process is produced according to the specifications.

How can a graph be created in Excel?

  • Count N points.
  • Calculate the data range R, the range R is the difference between the largest and smallest value in the sample.
  • Select the number of chapters or periods.
  • Calculate the category width.
  • Prepare a check sheet or check sheet to summarize the data on it.
  • Count the number of parts in each period or the frequencies in each category.
  • Draw the graph and put frequencies on the vertical axis, and the on the horizontal axis the intervals.

2. Fishbone diagram

It is also called the cause-and-effect scheme, and it is the scheme established by “Koroa Ishikawa.” This method looks at the various root causes and possibilities behind the problem, and they are collected to choose the real cause. In this scheme, many different factors such as man, machine, method, material, measurement, and environment are taken into consideration when researching. The causes or factors are grouped into six major groups to identify the potential source of the problem while keeping the chart organized.

How to create a fishbone diagram

Usually, the team meets and a fishbone diagram is made during the meeting. It is drawn on flipchart paper or a whiteboard. With the problem identified, teams can take the following steps to create the diagram: first draw the head of the fish, which is a square inside which writes a statement of the problem, then draw a horizontal line with An arrow pointing to the head of the fish, which serves as the backbone of the fish, and then several arrows emerge from the horizontal line that represents the initial bones of the fish. Accordingly, it determines at least four central causes that are likely to be the cause of the problem.

It can also include several general categories that we mentioned earlier, such as people, the environment, measurements, equipment, or others. Team members then confer on each cause separately, sharing ideas and information related to that cause, and writing down the contributing factors in the corresponding part of the cause.

When do we use a fishbone diagram?

  • To identify the possible causes of the problem, and the contributing factors.
  • To avoid recurring problems and employee fatigue.
  • To develop a problem-solving product.
  • To ensure that any procedures put in place to resolve the issue are correct.

3. Scheme of paper examination

The examination sheet is used to collect, analyze and record data, and this data may be opinions, observations, or numerical data, as it collects data that indicates the number of times a certain value has occurred in the form of signs or statistics, which helps to quickly identify defects or related problems Product or process and its solution, data collection is important to solve problems and provide further action.

When the data collected is quantitative in nature, it is called a score sheet, and the check sheet is used to collect data, identify the type of problem, defects, or non-conformities, and distinguish between fact and opinion. It is also used when collecting data from different machines, sites, people, etc.

Benefits of the Examination Paper Scheme

  • It helps to detect how many times the same problem recurs.
  • It helps to collect records and systematically maintain data, and analyze this data for corrective action.
  • This chart also helps as an initial data collection tool in making histograms, graphs, and Pareto charts.

4. Scatter plot

A scatter plot is also known as a correlation plot. A scatter graph shows the value of two variables of interest, establishes a relationship between the problem and the influencing causes and shows the relationship between them or two sets of numeric data either positively or negatively.

When do we use a scatter plot?

  • When there is associated numeric data.
  • When the dependent variable has multiple values ​​for each value of the independent variable.
  • When trying to determine if two variables are related like:
  • 1. While identifying possible causes of problems.
  • 2. After brainstorming the causes and effects use a fishbone diagram, to ascertain whether there is a particular relationship and effect.
  • When testing whether two seemingly related effects occur for the same reason.

Benefits of a scatter plot

  • A powerful tool for plotting the distribution of data in two dimensions, which helps to detect and analyze pattern relationships between the two variables of quality and compliance, both as an independent variable and a dependent variable.
  • Understanding whether there is a relationship between them, and discovering the type of relationship between them, whether it is strong or weak.
  • The shape of a scatter graph often shows the degree and direction of the relationship between two variables, and the correlation may reveal the causes of the problem.
  • Scatter plots are useful for regression modeling.
  • The chart can show if the association between the two variables is positive or negative or indicate that there is no association.

5. Shewhart charts

Also called a control chart, this chart helps to use collected data to monitor process centralization or process behavior against defined control limits and is an important tool for revealing the source of process variations found in manufacturing processes. It is widely used in quality control techniques and helps to make certain decisions, such as when to remove common differences.

When is a control chart used?

  • When you want to control running processes and directly find and solve problems.
  • When you want to predict the expected extent of the process.
  • When analyzing patterns of process variation from special (uncommon) or common causes.
  • When determining whether a quality management project aims to identify and prevent specific problems, or to bring about substantial changes.

6. Pareto charts

The Pareto chart is particularly helpful in focusing on important and affecting problems, narrowing the scope of the problem, and giving priority to remedial action. This scheme relies in its system on the rule of 80 - 20, as it shows that 80% of the problems are caused by 20% of the reasons and that the remaining 20% ​​of the problems or failures are caused by 80% of the reasons that are seen as trivial.

When do we use a Pareto chart?

  • A Pareto chart is used when you want to analyze why problems are recurring in a process.
  • When there are many problems and you want to focus on the most important ones.
  • When communicating with others about your data.
  • It is also used when analyzing the general causes of any problem.

Benefits of a Pareto chart

  • It helps to identify vital important items from among the trivial ones.
  • Shows the relative importance of the causes of the problem, using the 80-20 rule we can solve 80% of the problems using 20% ​​of the resources.
  • It also helps to understand defects and how they affect products.
  • Easy to analyze data with a Pareto chart, and also very useful in various Six Sigma projects, QCCk, Seven QCk, etc.

7. Flow charts

Also called flowcharts, flow planning predicts problems within a process, breaks down complex processes in any area in an easy-to-understand manner, shows changes in the process when improvements are made, and is one of the best tools that can be used to improve processes.

When is a flow chart used?

This diagram is used when you want to know where the bottlenecks or malfunctions are in the processes, as the diagram helps to provide a picture of what the process will look like, and helps to know the problems within the process. When improvements are made to the product, this flowchart helps show changes in the process and helps show how any new workflow works.

Other quality control tools

As we mentioned earlier, there are many quality control tools, and after mentioning the seven most famous, we append these five tools:

1. Stratification scheme

In this scheme, data, things, and people are divided into homogeneous categories or groups called strata for sorting. Separating and sorting data helps to define its meaning, and to discover patterns that may be invisible. This scheme is used when a set of data is collected from different sources, such as data collected from machines or humans.

Information related to data sources may strongly affect the final results of data analysis, so to obtain good results, this point must be taken into consideration, and stratified analysis allows an understanding of data during and after collection, even before collection.

2. Matrix diagram

It shows the relationship between different elements and works to clarify problems, and is used in many areas, such as analyzing market surveys, planning new products, and others.

3. Stock chart (Gantt chart + CPM chart, PERT chart )

The use of an arrow diagram is very effective for controlling and understanding schedules, it is also effective for illustrating the tasks required to carry out plans, and it is widely used in technical areas of program evaluation and review.

4. KJ affinity diagram

This chart can be used to accurately define the problem, and to find new and different solution strategies, as it is unique in this matter.

5. Tree diagram

Also known as a pyramid or organization diagram, this diagram has the advantage of facilitating agreement among the team.

When should the seven quality tools be used?

  • The seven quality tools can be implemented during quality control, when product quality improvement is desired, in SIX SIGMA, Six Sigma implementations, and in the PDCA cycle to improve quality management.
  • The following diagrams can be used in the first stage of measurement and definition: fishbone diagram, Pareto diagram, cause and effect diagram, and control diagram.
  • In the advanced stages of evaluation and analysis, scatter plots and histograms can be implemented.
  • To improve product quality, a control chart can also be used.

The benefits of the seven quality tools

Quality control tools are of great importance, as they have a major role in:

  • Solve problems related to products and services, and make business decisions and judgments.
  • Then it is of great importance in improving products in terms of quality, services provided, and operations.
  • It continuously contributes to raising and improving quality levels and obtaining customer satisfaction.


The advantages of the seven quality control tools also improve the problem-solving and analytical skills of employees, encourage team spirit and enhance cooperation, and help companies and institutions control and manage the production process.

Among the uses of the seven quality tools is also that it helps in identifying the various sources of differences in the process, always identifying the roots of problems and working to solve them scientifically and logically, and they are the most effective tools in addition to being easy to implement, understand and quick in completion, as they take a very short time to solve any problem.

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