denotes data item probability distribution probability distribution parameter A member of a set of quantities that unambiguously defines a probability distribution function. SEVCO Parameters serve different roles in defining distributions. Location parameters define the position along the range of possible values. Shape and scale parameters define the dispersion around the expected value. When the probability distribution parameters have values, the set of values defines a particular probability distribution function. When a statistic applies to a specific set of data, the specific set of data is called a sample and the statistic is called the sample statistic. Likewise, when a probability distribution parameter applies to the group from which a sample may be derived, the group is called a population and the probability distribution parameter is called a population parameter. Brian S. Alper, Harold Lehmann, Kenneth Wilkins, Joanne Dehnbostel Philippe Rocca-Serra ready for release