Pareto Analysis.

What is Pareto's Analysis?

Every Failures is the result of a few causes, and not all cause are of equal importance. Some Cause are more significant than the others. Pareto Analysis, underlines and operates this philosophy of "vital few;trivial many". It is technique of identify vital cause by arranging the data, according to the descending order of there frequency of occurrence.

History :

Pareto's diagram is the outcome of study conducted by Vilfredo Pareto to study the phenomenon of wealth in his country. Pareto observed that i n his native country, 80% of the wealth was held by only 20% of the population. He eventually realized that he had discovered a universal law-around 20% of the activity cause 80% of the defect.

How to making Pareto's Chart:


  • Selecting the problem and identify cause into a handful of categories. For example, for a problem of " Frequent Bearing Failure of Pump", possible categories of the cause may be lack of lubrication, misalignment, improper fitment, Vibration, Wrong selection of Bearing etc.
  • Select the standard unit of measurement (For example Frequency of failure or number of occurs, or breakdown time)
  • Select the time period over which data the collected ( for example Minutes or Hours or no of occurrence)
  • Collect the necessary data on each category and summaries result.
    • It is generally convenient to create a three column table having heading as " error category" Frequency (or cost), and "percentage of total". This information can be taken directly from the check list.
  • Rearrange the data in the descending order of the frequency or cost.
  • Organised the Pareto chart.
Making the Pareto graph involve the following steps:

  1. Draw two vertical axis, one on either side of a horizontal side axis (Leaving enough space on the horizontal axis to list the problem categories). Marks the frequency of occurrence of the problem along left vertical axis, and percentage along right vertical axis.
  2. Divide the horizontal axis into interval equal to the number of categories.
  3. List down the categories from left to right, in their order of decreasing frequency or cost.
  4. Construct a bat or rectangle above each category, with the height being equal to the frequency or cost.
  5. Draw the cumulative line/curve (Pareto's Curve) by plotting each point at the right hand corner of each bar and them connecting these points.
  6. Write all necessary information concerning the diagram.




Pareto chart