He found that the graves he was uncovering contained no evidence of their dates and their discrete nature meant that a sequence could not be constructed through their stratigraphy. The assumption that design styles follow a bell curve of popularity – starting slowly, growing to a peak and then dying away as another style becomes popular – provides the basis for frequency seriation.
Petrie listed the contents of each grave on a strip of cardboard and swapped the papers around until he arrived at a sequence he was satisfied with. It also assumes that design popularity will be broadly similar from site to site within the same culture.
In archaeology, seriation is a relative dating method in which assemblages or artifacts from numerous sites, in the same culture, are placed in chronological order.
Where absolute dating methods, such as carbon dating, cannot be applied, archaeologists have to use relative dating methods to date archaeological finds and features.
In 1971, Kendall proposed the use of multidimensional scaling techniques for seriation problems, and this approach has also been used by some other scientists (see Baxter 2003, pp. Baxter also presents a review of statistical methods for seriation and a description of these approaches (pp. Today, the most popular seriation method both for contextual and frequency problems is based on correspondence analysis. Using this technique, not only the sequence of the objects but also those of the design styles is established.
The sequence of the first axis of a correspondence analysis is considered the best seriation order (Shennan 1997, p. Note that external evidence is needed to establish the direction of the sequence calculated, i.e.
He reasoned that the most accurate sequence would be the one where concentrations of certain design styles had the shortest duration across the sequence of papers (Renfrew and Bahn 1996, p. In addition, it is vital that the lifespans of the different design styles overlap. to form groups of objects belonging to the same design style is by no means trivial.
Following these rules, an assemblage of objects can be placed into sequence so that sites with the most similar proportions of certain styles are always together (Lock 2003, p. Creating a typology frequently is the basis of a seriation.
For example, knives in early medieval times in Europe are said to show no chronological variation.Initially 60 contexts (called units in Win Basp) were created along with 50 types.The contexts were labeled in chronological order by numbers 01 to 60, the types are labeled in the form T00001 to T00050.In Europe, it has been used frequently to reconstruct the chronological sequence of graves in a cemetery (e.g.Jørgensen 1992; Two different variants of seriation have been applied: contextual seriation and frequency seriation (Renfrew and Bahn 1996, pp. Whereas contextual seriation is based on the presence or absence of a design style, frequency seriation relies on measuring the proportional abundance or frequency of a design style.
This is called the arch effect by Hill and Gauch (1980).