Statistical Tools

WHAT ARE 7 QC TOOLS?

The?7 quality tools?are simple graphical and statistical tools but very powerful in solving quality problems and process improvement. These statistical tools are very easy to understand and can be implemented without any complex analytical competence or skills.

The?7 tools of quality?are generally used by?quality control?and?quality assurance?engineers to solve product or process-related quality issues on a daily/weekly/monthly basis and to reduce/eliminate non-value-added activities like product rework, repair, and rejection.

WHY DO WE NEED?7 QC TOOLS?

We need Quality Tools for:

????????Problem Solving – making decisions & judgments.

????????For Process Measurement.

????????For continual improvement in products, processes, and services.

????????To improve?Quality, Productivity, and Customer Satisfaction.

????????“95% of the problem is solved when clearly defined”

????????“95% of quality-related problems in the organization can be solved by using seven fundamental quantitative tools.”

7QC Tools benefits

The major benefits of QC tools are:

????????To analyze and solve quality problems effectively.

????????Improve product and process?quality.

????????Enhance customer satisfaction.

????????Reduce cost due to poor quality.

????????Helps in investigating the potential causes and real root cause of the problem for taking effective countermeasures.

????????Check sheet helps in data collection and recording for quality problem analysis.??

????????Identify and reduce the?process variation?using the?SPC quality tool.

????????Pareto QC tool helps to narrow down the quality problem using the 80/20 rule.

????????Helps in identifying the various sources of variations present in the process.

????????Improve the employee’s analytical and problem-solving skills.

?7 Basic Quality Management Tools?

Quality management tools listed below were greatly emphasized by Kaoru Ishikawa, who was instrumental in creating total quality management and maximizing productivity by improving the quality of deliveries in the manufacturing industry. These seven basic quality management tools are also known as the ‘old’ seven or the ‘first’ seven. They are:

·???????Cause and effect diagram or the Fishbone diagram

·???????Control chart

·???????Pareto chart

·???????Stratification

·???????Check sheet

·???????Histogram

·???????Scatter diagram

?1. Cause and effect diagram or the Fishbone diagram

????????Kaoru Ishikawa created the Fishbone Diagram?or the cause-and-effect diagram. It was created as a means for problem-solving purposes.

????????The diagram is also referred to as a Fishbone diagram because it resembles a fishbone upon completion and also sorts ideas into useful categories until we can identify the root cause of the problem.

????????To use this tool, you first need to identify and state the problem as a question. This will help in brainstorming as each question should have an answer. Then you will list the major causes of the problem on the spine, which consists of one line across the page horizontally and a vertical line drawn as branches or bone.

?2. Control Chart

Control charts are used to plot data points over time and give a picture of the movement of that data. Control charts are used to compare current data to control limits which leads to conclusions on the consistency of process variation. The main purpose of the control chart is to determine whether the process is stable within the current conditions. The control chart is a type of graph that is used to plot the process data in a timely sequence.

3. Pareto Chart

????????A Pareto chart is also known as the 80-20 rule of quality management. These problems are listed out as 80% of all problems, and their causes are listed out to be 20% of the biggest factors.

????????A Pareto chart is a combination of a line graph and a bar graph. The values are shown by using the bar graph in the Pareto chart, and the line graph shows the total impact.

????????The main purpose of the Pareto chart is to highlight the most important factors that are the reason for the major cause of the problem or failure.

????????To construct a Pareto Chart, a different range of data is divided into groups and is called segments or categories.

?4. Stratification

Stratification is used to divide different factors that could affect the quality of delivery into separate groups. All the collected data is split up to create and observe different patterns of factors that affect quality. The stratification method is widely used for data analysis in terms of quality assurance.

5. Check Sheet

????????A check sheet is quality management and assurance tool used to find the frequency of an error or problem or a specific value.

????????A check sheet is a structured quality tool that is used to collect data. It is a type of prepared form for analyzing data and it can be adapted for a variety of purposes.

????????With a checklist, you can list down the important checkpoints or events in a tabular or metrics format. The Check Sheet is typically a list of questions or problems, in a document or spreadsheet.

?????????It is also used during the review process, to ensure that all the required steps and necessary pre-requisites have been completed.

6. Histogram

??A histogram helps quality analysts and management professionals accurately analyze different types of information they have available on different data groups to help create controls to improve the quality of any process.

??To construct a histogram, it is necessary to divide the range of values into specific intervals of five, ten, fifteen, etc. These intervals are known as bins which are consecutive and adjacent.

??The low-performing areas show up in less frequency on the histogram, and quality management professionals can then find the root cause of the problem and solve it.

??The examples to measure data in the histogram can be the number of new students joined, the number of new patients registered, etc.

7. Scatter Diagram

A scatter diagram is used to find the relationship between A and B. For example, if B is facing an issue with packaging, a scatter diagram can be used to find A, which is the main reason that B takes place. This way, all possible causes to the defects to the quality of a product or process can be identified easily, after which the quality management professionals can create and implement focused solutions to solve the main cause.