This presentation will address an important feature of archaeological analysis: how we manage the uncertainty associated with our traditional relative dating of archaeological artefacts. It emphasises the need to develop more explicitly probabilistic methods for assigning artefacts to particular chronological periods, and as a case, study, draws upon some 14,000 potsherds from an intensive surface survey of the Greek island of Antikythera that have been treated with these issues in mind from the outset. I consider several statistical methods that can be useful for understanding how the uncertainty associated with one period of time may be shared with another and how these shared uncertainties propagate into our spatial analysis and/or subsequent interpretation. Mapping such uncertainty in a vairety of ways can not only allows us to evelop more sophisticated interpretations, given the present state of our knowledge, but also allow us to identify where further fieldwork or object re-study can most profitably by invested. Finally, many of these challenges have implications for field practice, and in particular for the type of excavations or survey strategies we might wish to promote, and I will also reflect on these wider methodological debates.