Precision and accuracy in applied 14 C dating: some findings from the Fourth International Radiocarbon Inter-comparison E.M. Scott a, ) , C. Bryant b , I. Carmi c , G. Cook d , S. Gulliksen e , D. Harkness a , J. Heinemeier f , E. McGee g , P. Naysmith d , G. Possnert h , H. van der Plicht i , M. van Strydonck j a Department of Statistics, University of Glasgow, Glasgow, G128QW, UK b NERC Radiocarbon Laboratory, Glasgow, UK c Weizmann Institute, Rehovot, Israel d SUERC, Glasgow, UK e NUST, Trondheim, Norway f University of Aarhus, Aarhus, Denmark g University College Dublin, Dublin, Ireland h University of Uppsala, Uppsala, Sweden i University of Groningen, Groningen, The Netherlands j KIK, Brussels, Belgium Received 30 September 2001; received in revised form 5 April 2002 Abstract Users in the Quaternary and Archaeological Sciences have expressed a general desire for significant improvements in the accuracy and precision of radiocarbon dating results in general but also allied to the measurement of small samples. The accuracy and precision of measurement has also been the focus of some attention within the 14 C community. As a result, the 14 C community has undertaken a wide-scale, far-reaching and evolving programme of inter-comparisons, to the benefit of laboratories and users alike, the most recent being completed in 2001. The information arising from the studies is important for the appropriate inter- pretation of the scientific evidence provided by 14 C analyses in calibration and construction of chronologies where assemblages of dates are frequently assessed. In this paper, some preliminary findings from the Fourth International Radiocarbon Inter-comparison, completed in 2001, will be reviewed and some conclusions drawn with regard to accuracy and precision of 14 C dates. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Radiocarbon dating; Inter-comparison; Precision; Accuracy 1. Introduction Much of chronology construction in archaeological science depends on radiocarbon dating. The quality of the chronology depends fundamentally on the quality of the measurements made in its support. Therefore, it is crucial that the quality of the measurements be assured as part of the overall quality assurance of the science underpinning the chronology. Measurement quality as- surance as implemented by the laboratory has a number of components, including the use of in-house reference materials, measurement of international standards, de- velopment and implementation of detailed procedural documentation and regular participation in laboratory inter-comparisons. This latter aspect of laboratory qua- lity assurance provides an independent check on labo- ratory performance, verifying both laboratory accuracy and precision. ) Corresponding author. Tel.: C44-141-330-5125; fax: C44-141- 330-4814. E-mail address: marian@stats.gla.ac.uk (E.M. Scott). Journal of Archaeological Science 31 (2004) 1209e1213 http://www.elsevier.com/locate/jas 0305-4403/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jas.2002.06.001