The Pareto Principle - or 80/20 Rule - states that 80% of the deliverable from a project is achieved with 20% of the effort and that the remaining 20% will require 80% of the effort.
Let’s begin with a little history to see where this principle comes from. It was first expressed in 1906 by the economist Vilfredo Pareto - who gave his name to the principle - while studying the property of soil in Italy.
However, it was actually Joseph Juran who popularized it as a rule that can be applied in general to a large number of contexts and uses. Since then, and in a simple and easily-remembered manner, the 80/20 Rule has stated that a large part of effort is focused on a contribution of residual value and that a large part of the final result can be achieved with little effort.
While it is true that these percentages are not precise and that this rule uses an arbitrary proportion, it is also true that it reveals a great truth that we can apply to project management and many other activities in our daily life. We devote a great deal of time to things that contribute little value in reality, which cause us to advance little towards achieving our goals. If we were capable of focusing ourselves and our team on that 20% of effort that obtains 80% of the results, everything would be much simpler.
Creating effort-value tables can help us identify this relationship. Prioritizing tasks based on their result and estimating the effort they require allows us to focus ourselves on the most efficient of them. We should identify which things are most important and bring us closer to established targets using the least effort and time.
It will not always be possible to apply the 80/20 Rule and we will sometimes need to accept that 80% of effort will be dedicated to tasks that contribute little value. However, if we are aware of this fact, we will be able to suggest measures to project clients or sponsors when needing to cut down on functionality, adjust deadlines or reduce costs because we will identify which tasks we should focus on.