1 Chapter 6 Quality Tools
2 The Seven Basic Quality Tools. Flowcharts Check Sheets Histograms Pareto Analysis Scatter Diagrams Control Charts Cause-and-Effect Diagrams
Flowcharts A flowchart is a visual representation of a process. A flowchart is a visual representation of a process. As a problem-solving tool, a flowchart can help investigators in identifying possible points in a process where problems occur. As a problem-solving tool, a flowchart can help investigators in identifying possible points in a process where problems occur. 3
Flowcharts 4
Flowcharts 5
Flowcharts The diamond shapes in the flowchart represent decision points in the process. The diamond shapes in the flowchart represent decision points in the process. Rectangular shapes represent procedures. Rectangular shapes represent procedures. The arrows show the direction of "flow" of the steps in e process. The arrows show the direction of "flow" of the steps in e process. 6
Flowcharts To construct a simple flowchart Begin by listing the steps in a process. Begin by listing the steps in a process. Then classify each step as either a procedure or a decision (or check) point. Then classify each step as either a procedure or a decision (or check) point. 7
Check Sheets A check sheet is a simple tool frequently used for problem identification. A check sheet is a simple tool frequently used for problem identification. Check sheets provide a format that enables users to record and organize data in a way that facilitates collection and analysis. Check sheets provide a format that enables users to record and organize data in a way that facilitates collection and analysis. This format might be one of simple checkmarks. This format might be one of simple checkmarks. 8
Check Sheets Check sheets designed on the basis of what the users are attempting to learn by collecting data. Check sheets designed on the basis of what the users are attempting to learn by collecting data. 9
Check Sheets 10
Check Sheets 11
Histograms A histogram can be useful in getting a sense of the distribution of observed values. A histogram can be useful in getting a sense of the distribution of observed values. Among other things, one can see if the distribution is symmetrical, what the range of values is, and if there are any unusual values Among other things, one can see if the distribution is symmetrical, what the range of values is, and if there are any unusual values 12
Histograms 13
Histograms 14
Pareto Analysis Pareto analysis is a technique for focusing attention on the most important problem areas. Pareto analysis is a technique for focusing attention on the most important problem areas. The Pareto concept, named after the nineteenth-century Italian economist Vilfredo Pareto, is that a relatively few factors generally account for a large percentage of the total cases (e.g., complaints, defects, problems). The Pareto concept, named after the nineteenth-century Italian economist Vilfredo Pareto, is that a relatively few factors generally account for a large percentage of the total cases (e.g., complaints, defects, problems). 15
Pareto Analysis The idea is to classify the cases according to degree of importance, and focus on resolving the most important, leaving the less important. The idea is to classify the cases according to degree of importance, and focus on resolving the most important, leaving the less important. Often referred to as the rule, the Pareto concept states that approximately 80 percent of the problems come from 20 percent of the items. Often referred to as the rule, the Pareto concept states that approximately 80 percent of the problems come from 20 percent of the items. 16
Pareto Analysis For instance, 80 percent of machine breakdowns come from 20 percent of the machines, and 80 percent of the product defects come from 20 percent of the causes of defects. For instance, 80 percent of machine breakdowns come from 20 percent of the machines, and 80 percent of the product defects come from 20 percent of the causes of defects. 17
Pareto Analysis Often, it is useful to prepare a chart that shows the number of occurrences by category, arranged in order of frequency. Often, it is useful to prepare a chart that shows the number of occurrences by category, arranged in order of frequency. Presumably, the manager and employees would focus on trying to resolve this problem. Presumably, the manager and employees would focus on trying to resolve this problem. 18
Pareto Analysis Once they accomplished that, they could address the remaining defects in similar fashion. Once they accomplished that, they could address the remaining defects in similar fashion. 19
Pareto Analysis 20
21
Scatter Diagrams A scatter diagram can be useful in deciding if there is a correlation between the values of two variables. A scatter diagram can be useful in deciding if there is a correlation between the values of two variables. A correlation may point to a cause of a problem. A correlation may point to a cause of a problem. 22
Scatter Diagrams 23
Scatter Diagrams 24
Control Charts Charts A control chart can be used to monitor a process to see if the process output is random. Charts A control chart can be used to monitor a process to see if the process output is random. It can help detect the presence of correctable causes of variation. It can help detect the presence of correctable causes of variation. 25
Control Charts 26
Control Charts 27
Cause-and-Effect Diagrams A cause-and-effect diagram offers a structured approach to the arch for the possible cause(s) of a problem. A cause-and-effect diagram offers a structured approach to the arch for the possible cause(s) of a problem. It is also known as a fishbone diagram because fits shape, or an Ishikawa diagram, after the Japanese professor who developed the approach aid workers overwhelmed by the number of possible sources of problems when problem solving It is also known as a fishbone diagram because fits shape, or an Ishikawa diagram, after the Japanese professor who developed the approach aid workers overwhelmed by the number of possible sources of problems when problem solving 28
Cause-and-Effect Diagrams This tool helps to organize problem- solving efforts by identifying categories of factors that might be causing problems. This tool helps to organize problem- solving efforts by identifying categories of factors that might be causing problems. Often this tool is used after brainstorming sessions to organize the ideas generated. Often this tool is used after brainstorming sessions to organize the ideas generated. 29
Cause-and-Effect Diagrams 30
Cause-and-Effect Diagrams 31
32
The Use of Graphical Tools 33
34