The Pareto distribution is a power-law probability distribution that is used in description of many observable phenomena, including the principle originally applied to describing the distribution of wealth fitting the trend that a large portion of wealth is held by a small fraction of the population. The Pareto principle or "80-20 rule" states that 80% of outcomes are due to 20% of the population. Only Pareto distributions with shape value =1.16 precisely reflect. it. The cumulative density function is given by F(x)={1(xxm)0x>xmx.