who is credited for creating a distinction between common and special cases of variation
Common cause and special cause (statistics) Common and special causes are the two distinct origins of variation in a process, as defined in the statistical thinking and methods of Walter A. Shewhart and W. Edwards Deming. Briefly, "common causes", also called natural patterns, are the usual, historical, quantifiable variation in a system, while "special causes" are unusual, not previously observed, non-quantifiable variation.
English law Since 1189, English law has been a common law, not a civil law system; in other words, no comprehensive codification of the law has taken place and judicial precedents are binding as opposed to persuasive. This may be a legacy of the Norman conquest of England, when a number of legal concepts and institutions from Norman law were introduced to England. In the early centuries of English common law, the justices and judges were responsible for adapting the system of writs to meet everyday needs, applying a mixture of precedent and common sense to build up a body of internally consistent law. An example is the Law Merchant derived from the "Pie-Powder" Courts, named from a corruption of the French pieds-poudrÃ©s ("dusty feet") implying ad hoc marketplace courts.