Hi, The 20:80 , aka Pareto rule applies in certain processes. Pareto states that in some cases, 20 percent of the input generates 80% of the output (obviously not intended to be exactly 20 and 80). Example: 20% of customers generate 80% of the revenues , or 20% of a list of problems in an operating system generate 80% of customer complaints, or 20% of the population owns 80% of assets. Anyway, my question is on how do determine if/when the Pareto distribution applies to a given situation , or if there are some general results on how to apply it. EDIT: I am trying to understand the type of data one would have to look at and, given the data, how one can "tease out" from the data whether there is a 20-80 relation. Thanks.