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The Pareto is undoubtedly one of the most used tools for the treatment of problems. Simple and visual, his interest is at a glance allow us to visualize the problems to be treated as a priority.


Vilfredo Pareto is an Italian born in 1848 in Paris. Graduated in engineering and then in sociology and economics, he will remain famous for his statistical tool called ” Pareto principle “ or rule of 80/20. Based on the fact that few causes cause the majority of the problems.

He observed among other things that in his time 20% of the population have 80% of the wealth. Generalized thereafter by other renowned statistician like J. Juran, this tool is now used to prioritize actions.

On its principle, the Pareto chart allows this to be concentrated on a small number of causes to simplify actions and reduce costs and time limits of actions while drastically reducing the onset of the problem, removing the causes of the main one.

The Pareto graph

The Pareto graph is quite simple, which is largely part of its diffusion. In the x-axis, we find the different possible causes related to the problem studied. In order, one finds the influence of these same causes on the problem, indicated in percentage.

Represented as Shape a histogram, one usually gets a graph called 80/20 that is complete with a curve that accumulates the percentage of influence.

In the above case, it is observed that the first 2 causes are the source of about 80% of the problem. The challenge is to focus on these two causes to drastically reduce the onset of the problem.

Pareto limit

Inadequacy of the rule of 80/20

However, there are times when rule 80/20 is not verified. One arrives then to graphs where all causes have a similar influence to see identical. In cases like these, the prioritization of actions is done via a Gain/cost matrix.

Pareto Pareto

In obtaining your Pareto, you will select the most influential cause to solve it first. But, is this really the real cause? Example: In a text written to the computer, we measure the causes of write slowdown. The first cause is the ” Corrections “. The aim is therefore to look for the causes of the corrections.


Joiner Associates (1995) – Pareto charts, Plain & Simple

G. Busino (1968) – Introduction to a history of Pareto sociology

M. McLure (1999) – Vilfredo Pareto : Critical assessments of leading economist

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