Rule 28 is Pareto principle (English: Pareto principle), (also known as? The 80/20 rule, which is an important minority rule and the sparse factor principle, points out that about 80% of the impact of many events comes from 20% of the reasons.

Management consulting? Joseph Zhu Lan and the Italian economist? Pareto put forward this principle, and in 1896? University of Lausanne? Noting the 80/20 connection, he pointed out in his first article "Political Economy" that about 80% of the land in Italy is owned by 20% of the population. Pareto observed that about 20% of peas planted in his garden produced 80% of peas.

This is the general principle of enterprise management. For example, "80% of sales come from 20% of customers". Many enterprise executives regard the 80/20 rule as a tool to maximize business efficiency. Richard Koch wrote a book "80/20 Principle", which showed the practical application of Pareto principle in enterprise management and life.

Mathematically, the 80/20 rule generally follows the power law distribution of a set of specific parameters (also known as? Pareto distribution), many natural phenomena have experience, showing this distribution.

Pareto principle is only related to? Pareto optimal. The relationship between tangent edges. Pareto formulated these two concepts under the background of income distribution and wealth distribution of population.

The term 80/20 is just a shorthand for general principles at work. In some cases, the distribution is close to 80/ 10 or 80/30. There is no need to add these two figures, because they are measures of different things (for example, "number of customers" and "number of expenses").

However, in each case, it does not exceed 100%, which is equivalent to what they have done. For example, the above-mentioned "64/4 method" (in which two figures do not include 100%) is equivalent to "80/20 method" (in which the sum of the two is 100%). Therefore, specifying two percentages independently will not lead to a wider distribution than specifying a larger distribution, and make the smaller distribution the complement of 100%. Therefore, it can add 100 symmetries at most.

For example, if 80% of the effects come from the top 20% sources, the remaining 20% of the effects come from the lower 80% sources. This is called "joint ratio" and can be used to measure the degree of imbalance: the joint ratio of 96: 4 is very unbalanced, 80:20 is significantly unbalanced (Gini coefficient: 60%), 70:30 is moderately unbalanced (Gini index is 40%) and 55:45 is slightly unbalanced.