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This week's Wiki-Wednesday topic is The Pareto Principle. An excerpt of the article is below, but you can click here to be connected to the rest of the page on Wikipedia. Many of us refer to the Pareto Principle in our work: when we look at historical spend, we might check to see how fragmented it is based on how many suppliers make up the top 80% of spend in a category. Or conversely, we might check compliance based on how many suppliers make up the bottom 20% of spend in that category. Most often, we make the broad statement that 80% of a company's spend is made with 20% of the supply base.

From Wikipedia:

The Pareto principle (also known as the 80-20 rule, the law of the vital few, and the principle of factor sparsity) states that, for many events, roughly 80% of the effects come from 20% of the causes.[1][2]

Business-management consultant Joseph M. Juran suggested the principle and named it after Italian economist Vilfredo Pareto, who observed in 1906 that 80% of the land in Italy was owned by 20% of the population; he developed the principle by observing that 20% of the pea pods in his garden contained 80% of the peas.[2]

It is a common rule of thumb in business; e.g., "80% of your sales come from 20% of your clients". Mathematically, where something is shared among a sufficiently large set of participants, there must be a number k between 50 and 100 such that "k% is taken by (100 − k)% of the participants". The number k may vary from 50 (in the case of equal distribution, i.e. 100% of the population have equal shares) to nearly 100 (when a tiny number of participants account for almost all of the resource). There is nothing special about the number 80% mathematically, but many real systems have k somewhere around this region of intermediate imbalance in distribution.[3]

80-20 is only a shorthand for the general principle at work. In individual cases, the distribution could just as well be, say, 80-10 or 80-30. There is no need for the two numbers to add up to 100%, as they are measures of different things, e.g., 'number of customers' vs 'amount spent'). However, each case in which they do not add up to 100%, is equivalent to one in which they do; for example, as noted above, the "64-4 law" (in which the two numbers do not add up to 100%) is equivalent to the "80-20 law" (in which they do add up to 100%). Thus, specifying two percentages independently does not lead to a broader class of distributions than what one gets by specifying the larger one and letting the smaller one be its complement relative to 100%. Thus there is only one degree of freedom in the choice of that parameter.

Some additional reading on the Pareto Principle from About.com

Where It Came From

After Pareto made his observation and created his formula, many others observed similar phenomena in their own areas of expertise. Quality Management pioneer, Dr. Joseph Juran, working in the US in the 1930s and 40s recognized a universal principle he called the "vital few and trivial many" and reduced it to writing. In an early work, a lack of precision on Juran's part made it appear that he was applying Pareto's observations about economics to a broader body of work. The name Pareto's Principle stuck, probably because it sounded better than Juran's Principle.

As a result, Dr. Juran's observation of the "vital few and trivial many", the principle that 20 percent of something always are responsible for 80 percent of the results, became known as Pareto's Principle or the 80/20 Rule.

What It Means

The 80/20 Rule means that in anything a few (20 percent) are vital and many(80 percent) are trivial. In Pareto's case it meant 20 percent of the people owned 80 percent of the wealth. In Juran's initial work he identified 20 percent of the defects causing 80 percent of the problems. Project Managers know that 20 percent of the work (the first 10 percent and the last 10 percent) consume 80 percent of your time and resources. You can apply the 80/20 Rule to almost anything, from the science of management to the physical world.

You know 20 percent of your stock takes up 80 percent of your warehouse space and that 80 percent of your stock comes from 20 percent of your suppliers. Also 80 percent of your sales will come from 20 percent of your sales staff. 20 percent of your staff will cause 80 percent of your problems, but another 20 percent of your staff will provide 80 percent of your production. It works both ways.

How It Can Help You

The value of the Pareto Principle for a manager is that it reminds you to focus on the 20 percent that matters. Of the things you do during your day, only 20 percent really matter. Those 20 percent produce 80 percent of your results. Identify and focus on those things. When the fire drills of the day begin to sap your time, remind yourself of the 20 percent you need to focus on. If something in the schedule has to slip, if something isn't going to get done, make sure it's not part of that 20 percent.

There is a management theory floating around at the moment that proposes to interpret Pareto's Principle in such a way as to produce what is called Superstar Management. The theory's supporters claim that since 20 percent of your people produce 80 percent of your results you should focus your limited time on managing only that 20 percent, the superstars. The theory is flawed, as we are discussing here because it overlooks the fact that 80 percent of your time should be spent doing what is really important. Helping the good become better is a better use of your time than helping the great become terrific. Apply the Pareto Principle to all you do, but use it wisely.

The Point

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