Seven methods of QC quality management

1. 1. Layer method

   Hierarchical method is to classify a large number of viewpoints, opinions or ideas on a specific topic into groups, and group a large amount of data or information collected according to their interrelationships and stratify them. The level method is generally used in combination with other seven methods such as Plato and histogram, and can also be used alone.

   

2. 2. Checklist

   A checklist is a method of listing the contents or items that need to be checked one by one, and then checking item by item regularly or irregularly, and recording the problem points, sometimes called a checklist or a spot checklist.

   

3. 3. Plato

   The use of Plato is based on the premise of the hierarchical method, and the items determined by the hierarchical method are arranged from large to small, plus a graph of cumulative values. It can help us find out key problems, grasp the important minority and the useful majority, and is suitable for numerical statistics.

   

4. 4. Histogram

   　The histogram is for the characteristic value of a product or process, using the principle of normal distribution (also called normal distribution), grouping more than 50 data, and calculating the number of occurrences of each group, and then using a similar histogram to describe in the on the horizontal axis.

   

5. 5. Cause and effect analysis diagram

   The so-called causal diagram, also known as the characteristic factor diagram, is mainly used to analyze the causal relationship between the quality characteristics and the possible causes that affect the quality characteristics. A tool for qualitative characteristics (consequences) and factors (causes) that may affect the characteristics. Also known as a fishbone diagram.

   

    

6. 6. Scatter plot

   The data corresponding to changes in the causal relationship are depicted on the XY axis coordinate system to grasp whether the two variables are related and the degree of correlation. This kind of graph is called "scatter diagram", also known as "correlation diagram".

   

    

7. 7. Control Chart

   It is a quality control method based on prevention. It uses the quality characteristic values ​​collected on site to draw a control chart, and judge the quality status of the production process of the product by observing the graphics.