In a simple random sample (SRS), all cases from a list have an equal chance to be chosen. Both eHRAF World Cultures and eHRAF Archaeology have simple random samples, but they are sampled from different lists. For eHRAF World Cultures, the SRS is randomly sampled from a list of cultures compiled from 8 different cross-cultural samples (Ember et al. 1992. Computerized Concordance of Cross-Cultural Samples. New Haven: Human Relations Area Files). For eHRAF Archaeology, the SRS is randomly sampled from the Outline of Archaeological Traditions (OAT) compiled by Peter N. Peregrine (2001, revised 2010. Human Relations Area Files) with the help of a Board of Advisors. The OAT attempted to catalogue all known prehistoric archaeological traditions.