The accuracy of radiocarbon dates

This article deals in detail with the various factors which affect the accuracy of radiocarbon dates. The familiar “error term” associated with each date and which caused so much confusion to users of radiocarbon dates in the early days of the method is derived from the statistical uncertainties of the measurements of radioactivity from which the date is calculated and is the only source of error which is capable of strict mathematical treatment. Other sources of error, as for example wrong attribution of the sample or human error in labelling, can be disastrously large on occasion, although they can usually be kept quite small. Errors arising from the effects of isotopic fractionation can be eliminated by the application of corrections based on mass spectrometric measurements of the stable carbon isotopes in the sample. However, it is now known that the most serious limitation on the accuracy obtainable by the radiocarbon method is set by the fact that the level of radiocarbon in the carbon exchange reservoir has not been constant in the past. Despite this limitation, however, the method is still the most important scientific aid to archaeological research to emerge since the end of World War II.