The principal value of a Pareto diagram is as a

The Pareto principle is that most things in our life are not commonly distributed.

Explanation:

Pareto chart shows that most of the things which we have in our life and the resources in our life are not equally distributed. The ratio is not always 50:50 according to this principle.

The most important use of a Pareto diagram is to show the most important factor among the set of factors that have been shown. Along with that it also shows the sources which lead to the common defects in the system and tries to solve those defects which occur most often.