n.choosing a portion of a body of records for permanent retention through a statistical process that ensures each file within the series has an equal chance of being included in the retained set; statistical samplingHull 1981, 11Any form of selection other than some types of systematic sampling and all random sampling will, in fact, be subjective even though the criteria laid down may be legal, fiscal or administrative in character, but whereas in theory it is perfectly proper for the officer of an agency to determine what will be useful to him and his successors for the purposes of the agency served, if a third party determines selection with research interests in mind then questions of validity and subjectivity inevitably arise.Hull 1981, 13As will be seen later ‘random’ sampling not only involves a haphazard selection but also requires that every piece in a series has an equal chance of being selected, the very an[t]ithesis of ‘systematic’ sampling.Cook 1991b, 38Three common types of sampling are simple random, systematic random and stratified random. Simple random sampling is where the 1,400 chosen numbers are applied randomly across the entire population. It is thus most appropriate for very homogenous, very short-lived series without significant internal geographical, gender, chronological or other bias.Lyle 2004, 8Random, or statistical, sampling is, in theory, the most objective of the three main sampling methodologies. It allows for every record within a sample equal opportunity to be chosen.choosing a portion of a body of records for permanent retention through a process that employs a pre-set pattern of selection to produce a sample of the whole; systematic random samplingCook 1991b, 38Perhaps the most appropriate method for archivists, therefore, is systematic random sampling, where only the first number is chosen randomly, and then every nth number thereafter is chosen until the full sample size (say 1,400 cases) is attained.Choosing a portion of a body of records for permanent retention through a process that ensures the retention of a statistical sample of each type or category of file within the series in the retained set at the same percentage as it was within the whole; stratified sampling or stratified random samplingCook 1991b, 38Stratified random sampling is where the whole is broken down into logical "strata" (which may be defined as parts or subgroups or geographic areas or file blocks of the whole - like the categories in the United States Justice Department litigation case files mentioned earlier), and then each stratum is randomly or systematically sampled, thus ensuring that no part is overlooked.
