Unless you’re total arch-math geeks: A Theoretically-Sufficient and Computationally-Practical Technique for Deterministic Frequency Seriation
Frequency seriation played a key role in the formation of archaeology as a discipline due to its ability to generate chronologies. Interest in its utility for exploring issues of contemporary interest beyond chronology, however, has been limited. This limitation is partly due to a lack of quantitative algorithms that can be used to build deterministic seriation solutions. When the number of assemblages becomes greater than just a handful, the resources required for evaluation of possible permutations easily outstrips available computing capacity. On the other hand, probabilistic approaches to creating seriations offer a computationally manageable alternative but rely upon a compressed description of the data to order assemblages. This compression removes the ability to use all of the features of our data to fit to the seriation model, obscuring violations of the model, and thus lessens our ability to understand the degree to which the resulting order is chronological, spatial, or a mixture. Recently, frequency seriation has been reconceived as a general method for studying the structure of cultural transmission through time and across space. The use of an evolution-based framework renews the potential for seriation but also calls for a computationally feasible algorithm that is capable of producing solutions under varying configurations, without manual trial and error fitting. Here, we introduce the Iterative Deterministic Seriation Solution (IDSS) for constructing frequency seriations, an algorithm that dramatically constrains the search for potential valid orders of assemblages. Our initial implementation of IDSS does not solve all the problems of seriation, but begins to moves towards a resolution of a long-standing problem in archaeology while opening up new avenues of research into the study of cultural relatedness. We demonstrate the utility of IDSS using late prehistoric decorated ceramics from the Mississippi River Valley. The results compare favorably to previous analyses but add new details into the structure of cultural transmission of these late prehistoric populations.
I’ve always found seriation fascinating, although I haven’t studied it much. It is, in fact, one of the very few truly archaeological contributions to science, although the theory behind it was always more or less implicit. But it was archaeologist who noticed that the frequencies of certain items vary in predictable ways that corresponded to, apparently, spatial and temporal dimensions. The paper, I think (I only perused it earlier), goes into that in some detail.
I tried something similar many years ago, translating a seriation program written by someone else (can’t remember who offhand, will get it later) in FORTRAN and really got into the method and algorithm in detail. Trouble was, it took some fudging to make it work, it wasn’t at all automatic, which is what they are into here. I also think the author fudged it in his American Antiquity paper. At any rate, give this a read, it will really give you a good background on the method.
I’ve also always wanted to do a detailed examination of the Americanist method of seriation compared to Petrie’s Sequence Dating and look at what sort of interaction (if any) went on while both were being developed. One of these days. . . .