Typology and seriation dating
Frequency seriation is applied in case of large quantities of objects belonging to the same style.An example are assemblages of pottery sherds each including roughly the same range of types though in different proportions.
In addition to temporal organization, seriation results may reflect assemblage differences in social status, age, sex or those resulting from regional variation (or a combination of two or more of these factors). 343) presents a seriation result of Danish hoards based on artefact types like daggers, axes, and swords.Flinders Petrie excavated at Diospolis Parva in Egypt in the late nineteenth century. 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.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. It also assumes that design popularity will be broadly similar from site to site within the same culture; 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.Kendall (1971) applied multidimensional scaling to the cemetery data of Münsingen, the resulting scatterplot showed the form of a horse-shoe where the graves were arranged on the curve according to their chronological order.Similarly, a mapping of the component scores for the first two axes of the correspondence analysis result will display a parabola if the design styles considered are controlled by one factor only (like chronology), this is called the arch effect by Hill and Gauch (1980).The correspondence analysis results shown in the figures below were calculated on the basis of 49 contexts with ideal seriation data, the scatterplot of the first two correspondence analysis axes shows the typical parabola shape.The display of the scores on the first and the third axes exhibits points lying on a third degree polynomial curve.Robinson based his frequency seriation method on a similarity matrix; 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, 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.the method does not tell whether the first object in the sequence is the oldest or the youngest object.If more than one factor is important, the arch effect may distort the results.Hill and Gauch (1980) presented a method to remove this effect.