C-14 datings can not only provide us with estimates of the absolute age of objects or occupation layers, but also, when available in sufficient numbers, with initial and terminal datings for cultural phases, thus defining their duration. The value of this is obvious: differential duration in different areas can at last provide definitive answers to long-disputed questions concerning the direction of cultural movement.Working with large numbers of C-14 dates is, however, not entirely free of problems. We are, for example, regularly confronted with larger differences between datings expected to be of similar age than can be accounted for by mere statistical error (Vogel, 1969a) or which can be explained by contamination or other simple causes. One can stop at this point and accept a limited testimonial value for C-14 dates (e.g. Steuer and Tempel, 1968), or one can try to go further by calculating average dates, assuming (for the most part incorrectly) that the chance of a date being too young is equal to its chance of being too old (Neustupný, 1968). The danger in this procedure is that one loses sight of the individual character of each determination: in fact one sample is much more securely associated and more closely contemporary with finds of a particular cultural phase than another, and the chance of contamination or admixture is different for each sample.Another problem is that the number of C-14 dates that one must take into consideration is often so large that they cannot be digested without some form of graphic presentation, and for this there is as yet no uniformity of practice.
Quantifying the contribution of established risk factors to cardiovascular mortality differences between Russia and Norway