PM Question of the Week - week 49 2014

Dear colleague, welcome to our "PM question of the week" newsletter for week 49 2014.

We specially like the seven "basic quality tools" introduced by the chapter 8 - Project Quality Management of the PMBoK, therefore this week we will focus on another one: the Pareto diagram. Let's introduce our weekly PMP exam question.

The following picture represents the Pareto diagram of the production process. In order to meet the product specification you need to reduce the number of defects by 80% at least. What is the best thing to do?

a. Eliminate issues 1, 2 and 3.
b. Reduce issues 1 to 5 by 80%.
c. Eliminate issues 3, 4 and 5.
d. It is impossible to tell.

Answer to question and explanation

The correct answer is a. Eliminate issues 1, 2 and 3.

Explanation: Pareto diagrams are used to determine the sources that cause most of the effects. Pareto diagrams are often associated to the "80/20 rule", that can be stated as follows "the 80 percent of the effects are determined by the 20 percent of the causes". In this week question the sources are represented by the issues, while the effects are the defects. Issue 1 is clearly causing the majority of the defects. In order to reduce defects by 80% it is necessary to eliminate issues 1, 2 and 3: in fact, even if the exact amount of defects that are caused by each issue is not provided, looking at the Total line in the Pareto diagram it is easy to recognize that issues 1, 2 and 3 together account for more than 80% of the total defects. Please note that answer b. Reduce issues 1 to 5 by 80%. is not correct, because the total amount of defects accounted for in the Pareto diagram is not 100%: you have to assume that there are other issues or causes not listed in the diagram.

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