New Book Part 9

Review

In my last post, we began our discussion on what I believe are the 4 best tools for problem solving.  I listed the four best tools as the Run Chart, the Pareto Chart, the Cause and Effect Diagram, and the Causal Chain.  I completed the last post by giving a brief description of the Run Chart and explained the basics of how to create one and how it can be used.  In today’s post we will look at more of these problem solving tools.

The 4 Best Tools for Problem Solving (con’t)

The Pareto Chart

While the run chart answers the questions of if and when a change has occurred, the Pareto chart is more of a comparative tool.  That is, if we suspect differences in performance between things like machines, people, or even days of the week, then we can visualize these differences with a Pareto chart.  The genesis of Pareto charts came from a most unlikely source.  An Italian economist, Vilfredo Pareto, was studying the distribution of wealth in Italy in the 19th century.  When he assembled his data, he discovered that approximately 80 % of the wealth in Italy was controlled by only 20 % of the population.  Later Dr. Joseph Juran, a noted American quality authority, further developed Pareto’s inadvertent discovery and so named this phenomenon the Pareto principle in Pareto’s honor.  Juran found that the Pareto principle applied to many different things like absenteeism, defects, accidents, etc. He found that many things typically align themselves and follow the principle that 80 % of problems are manifested in 20 % of the items with the problem. Let’s look at an example of this tool.

Suppose that a machine is experiencing faults and we have been asked to look into the problem.  We assemble the data and notice that the frequency of the faults is not the same every day. If we were to arrange the data as a Pareto chart, by day of the week, as in Figure 2.4, we see that the chart of this data validates what we believed was true.  The Pareto chart gives a picture of the days of the week and clearly shows us that we have a severe problem with faults on Monday and then the faults gradually decrease as the week progresses until Friday when they cease to exist. By knowing that Monday is the worst day for faults, we can focus our efforts on comparing what is unique or different on Monday compared to the best day of the week, Friday.

Pareto charts are really quite simple to create.  Along the horizontal or x-axis we simply place what we are comparing (e.g. operators, machines, etc.), and then place whatever we are measuring along the vertical or y-axis.  Now what could be more straightforward than that?

In my next post, we continue our discussion on these four important tools.  As you go through my postings, if you have any questions for me, send me an email to ras8202@live.com.

Bob Sproull