Determining when rare (zoo-)archaeological phenomena are truly absent

Archaeologists are regularly faced with the dilemma of determining if the absence of a class of item is the result of that class never having been present in an area or if its absence is the result of sample deficiencies. This dilemma is especially apparent when a class of item is rare and has a patchy distribution. Comparison of samples that lack specimens of the class with samples that have specimens reveals criteria of an adequate sample. These criteria must be met by a sample in order to convincingly argue that the class of item was never present in the area from which the sample derives, and to provide guidelines for developing sampling designs aimed at discovering rare phenomena.