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Learn about the seven basic quality tools including flowcharts, check sheets, histograms, pareto analysis, scatter diagrams, control charts, and cause-and-effect diagrams. These graphical tools can help identify and analyze problems in processes.
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Chapter 6 Quality Tools
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. • As a problem-solving tool, a flowchart can help investigators in identifying possible points in a process where problems occur.
Flowcharts • The diamond shapes in the flowchart represent decision points in the process. • Rectangular shapes represent procedures. • The arrows show the direction of "flow" of the steps in e process.
Flowcharts To construct a simple flowchart • Begin by listing the steps in a process. • Then classify each step as either a procedure or a decision (or check) point.
Check Sheets • 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. • This format might be one of simple checkmarks.
Check Sheets • Check sheets designed on the basis of what the users are attempting to learn by collecting data.
Histograms • 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
Pareto Analysis • 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).
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. • Often referred to as the 80-20 rule, the Pareto concept states that approximately 80 percent of the problems come from 20 percent of the items.
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.
Pareto Analysis • 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.
Pareto Analysis • Once they accomplished that, they could address the remaining defects in similar fashion.
Scatter Diagrams • 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.
Control Charts • 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.
Cause-and-Effect Diagrams • 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
Cause-and-Effect Diagrams • 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.
