At the heart of this progress is a process of substitution. Resources that have weak effects in any particular use are not used, or are used sparingly. Resources that have powerful effects are used as much as possible. Every resource is ideally used where it has the greatest value. Wherever possible, weak resources are developed so that they can mimic the behaviour of the stronger resources.

Why should you care about the 80/20 Principle? Whether you realize it or not, the principle applies to your life, to your social world and to the place where you work. Understanding the 80/20 Principle gives you great insight into what is really happening in the world around you.

The reason that the 80/20 Principle is so valuable is that it is counterintuitive. We tend to expect that all causes will have roughly the same significance. That all customers are equally valuable. That every bit of business, every product and every dollar of sales revenue is as good as another. That all employees in a particular category have roughly equivalent value. That each day or week or year we spend has the same significance. That all our friends have roughly equal value to us. That all enquiries or phone calls should be treated in the same way. That one university is as good as another. That all problems have a large number of causes, so that it is not worth isolating a few key causes. That all opportunities are of roughly equal value, so that we treat them all equally. We tend to assume that 50 per cent of causes or inputs will account for 50 per cent of results or outputs. There seems to be a natural, almost democratic, expectation that causes and results are generally equally balanced. And, of course, sometimes they are. But this ‘50/50 fallacy’ is one of the most inaccurate and harmful, as well as the most deeply rooted, of our mental maps.

The key point is not the percentages, but the fact that the distribution of wealth across the population was predictably unbalanced.

In business, many examples of the 80/20 Principle have been validated. 20 per cent of products usually account for about 80 per cent of dollar sales value; so do 20 per cent of customers. 20 per cent of products or customers usually also account for about 80 per cent of an organization’s profits. In society, 20 per cent of criminals account for 80 per cent of the value of all crime. 20 per cent of motorists cause 80 per cent of accidents. 20 per cent of those who marry comprise 80 per cent of the divorce statistics (those who consistently remarry and redivorce distort the statistics and give a lopsidedly pessimistic impression of the extent of marital fidelity). 20 per cent of children attain 80 per cent of educational qualifications available. In the home, 20 per cent of your carpets are likely to get 80 per cent of the wear. 20 per cent of your clothes will be worn 80 per cent of the time. And if you have an intruder alarm, 80 per cent of the false alarms will be set off by 20 per cent of the possible causes. The internal combustion engine is a great tribute to the 80/20 Principle. 80 per cent of the energy is wasted in combustion and only 20 per cent gets to the wheels; this 20 per cent of the input generates 100 per cent of the output!

The 80/20 Principle asserts that a minority of causes, inputs or effort usually lead to a majority of the results, outputs or rewards. Taken literally, this means that, for example, 80 per cent of what you achieve in your job comes from 20 per cent of the time spent. Thus for all practical purposes, four-fifths of the effort—a dominant part of it—is largely irrelevant. This is contrary to what people normally expect.

Ich habe mal versucht, ein bisschen rauszukriegen, ob denn diese 20 Prozent in der Praxis erreicht werden. Das scheint unterschiedlich zu sein. Aber zum Beispiel beim größten deutschen und auch weltweiten Internetknoten, dem DE-CIX in Frankfurt, liegt die regelmäßige durchschnittliche Auslastung unter 20 Prozent, sodass man davon ausgehen kann, dass der Bundesnachrichten-dienst den DE-CIX komplett überwachen dürfte.

Das G-10-Gesetz sagt, dass die Telekommunikations-überwachung sich maximal auf 20 Prozent der Übertragungskapazität des jeweiligen Übertra-gungswegs beziehen darf.

An effective data management program would enable a user 20 years or longer in the future to discover , access , understand, and use particular data [ 3 ]. This primer summarizes the elements of a data management program that would satisfy this 20-year rule and are necessary to prevent data entropy .