4.4.1 Process improvement tools
Flow charts are commonly used in describing processes. They are a schematic representation of the steps in any process. In the management process, they identify the role of each person in any task. This assists in defining clearly the role of individuals and in giving them an understanding of their role in the bigger picture. They can understand clearly who is the internal and external customer and who they should be communicating with to improve the process. Flow charts are often used to identify problem sectors of the production process and thus focus attention on the area that needs improving.
Activity 4.4
In the space below, draw a flow chart of the process of enrolment to study on this course, from the time you first enquired to the time you received the first study materials. Identify potential areas for improvement in the process.
Check sheets are commonly used to collect data and are designed in such a way that data that must be collected from any source is not missed. This organised way of collecting data also ensures that data can be easily analysed. Check sheets can take various shapes and can be designed to cover a wide range of processes and applications.
Histograms are basic tools of descriptive statistics. They are graphical descriptions of frequency distributions. They allow visual display and understanding variations in any process. They also allow the showing of the limits of operation variables and indicate when processes have crossed those limits. Over time, the tracking of performance improvements can be shown easily by histograms.
Cause and effect diagrams were originated by Dr Koaru Ishikawa and are often called Ishikawa diagrams, or fishbone charts. They were made famous by Deming in developing his quality tools. To be able to identify causes of problems, the major inputs and possible causes can be identified on a cause and effect diagram. This diagram becomes a powerful tool for brainstorming sessions and collecting ideas on various sub-processes.
Pareto diagrams are named after Vilfredo Pareto who found that 85% of the problems are caused by 15% of the causes (he said people). This principle was made famous by Juran, who applied the same thinking to process characteristics. Juran said that the vital few (15%) caused the greatest number of variations, while the useful many (85%) caused only a few. In depiction, a Pareto diagram is merely a histogram that shows frequencies from the largest to the smallest in order. It therefore clearly identifies where the largest number of problems lie and where most attention should be focused for improvement.
Scatter diagrams depict graphically the output of regression analyses. They are useful in that they provide a visual depiction of relationships between various variables. The variables are the possible causes and effects that are obtained from cause and effect diagrams. When plotted, the causes and effects are shown in their relationship to each other.
Control charts are line graphs in which data is plotted over time. On the vertical axis, the measurements are shown, sometimes with upper and lower limits marked. The horizontal axis shows a time scale. The chart looks very similar to seismic graphs of earthquakes, or graphs of heart performance as shown by electrocardiogram tests. In process control, the upper and lower limits indicate the parameters within which the performance should remain. If a printout were taken of the air-conditioning function, such a chart would indicate when the air-conditioning cut in as the temperature in the space rose and where it cut out as the temperature fell below the control limits.
Activity 4.5
In the space below, draw a histogram, a Pareto diagram, a cause and effect diagram and a control chart. Label the axes with some appropriate parameters for your own working situation.
What is the value of each in process control?
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