There are a large number of instances of Power Law relationships that have been identified across a wide variety of situations. In general, a power law relationship is one in which 'one quantity varies as the power of another'.

 Examples include:

Pareto Distribution - often known as the 80:20 law in which 20% of the items produce 80% of the results

Zipf's law - in a body of natural language, the frequency of any word is inversely proportional to its rank in the frequency table

Lotka's Law - the frequency of authors creating n publications is approximately equal to K/(n^a) where K is a constant and a is approximately equal to 2

Klieber's Law and other allometric laws - predicting body shape,size and behaviour relations in animals

Stefan-Bolzmann Law - the emitted energy-temperature relationship of a black body

Power Laws are typified by scale invariance (linear plot of log of f(x) and x) and universality (structurally similar foundational processes)

Power law relationships amongst variables are found when individual elements interact in the course of their behaviour. I hypothesised the following Power Law Indicator for Social Systems on the basis of a variety of research projects involving analysing data for creating interventions for social programs.

Power Law Indicator Hypothesis  for Social Systems:

When human behaviour data exhibits the features of Power Law relationships, this indicates the behaviour is shaped by human interactions.

This indicator appears to be a useful diagnostic in identifying appropriate social program interventions.It indicates where social programs aimed at intervening in the sociocultural and communication  realms are likely to be more effective than intervening directly, and vice-versa.