Seriation by constrained correspondence analysis: A simulation study

One of the many areas in which Correspondence Analysis (CA) is an effective method, concerns ordination problems. For example, CA is a well-known technique for the seriation of archaeological assemblages. A problem with the CA seriation solution, however, is that only a relative ordering of the assemblages is obtained. To improve the usual CA solution, a constrained CA approach that incorporates additional information in the form of equality and inequality constraints concerning the time points of the assemblages may be considered. Using such constraints, explicit dates can be assigned to the seriation solution. In this paper, we extend the set of constraints that can be used in CA by introducing interval constraints. That is, constraints that put the CA solution within a specific time-frame. Moreover, we study the quality of the constrained CA solution in a simulation study. In particular, by means of the simulation study we are able to assess how well ordinary and constrained CA can recover the true time order. Furthermore, for the constrained approach, we see how well the true dates are retrieved. The simulation study is set up in such a way that it mimics the data of a series of ceramic assemblages consisting of the locally produced tableware from Sagalassos (SW Turkey). We find that the dating of the assemblages on the basis of constraints appears to work quite well.