A ‘match–no match‘ numerical and graphical kernel density approach to interpreting lead isotope signatures of ancient artefacts

Abstract

A new method for interpreting lead isotope ratios of artefacts is presented: a numerical and graphical 'match-no match' with possible raw materials. By calculating the definite integral under the kernel density estimate plot of different mining districts, using open-access software and legacy data, the relative probability that an object is made of an ore is indicated. A match with the reference data set may indicate the true origin, while no match indicates an unknown origin, that is, not present in the data set of mineral resources. Likewise, the composite or recycled nature of artefacts can be investigated in a probabilistic manner.

Maritime connections in the Western Mediterranean and access to copper resources in the Balearic Islands during the Late Bronze Age: Isotopic characterization of the bronze deposit at Es Mitjà Gran, Mallorca

“…For this, it was chosen to use the method described by Birch et al (2020) (for details see Data S2 in the additional supporting information). In addition, the results were evaluated following the methodology described by Ceuster and Degruse (2020), based on the application of kernel density calculations and relative probability percentages for the isotopic ratios 206 Pb/ 204 Pb, 207 Pb/ 204 Pb and 208 Pb/ 204 Pb. Due to the heterogeneous nature of the isotopic values of samples from the same region, in many cases these calculations do not allow discriminations.…”

Transformative copper metallurgy in Chalcolithic Cyprus: a reappraisal

“…Not all isotopes are taken into account simultaneously in any such graphical comparison. Moreover, lead isotopic data have a non-normal distribution and evolve according to particular laws of radioactive decay and geochemistry, which have been neglected in archaeological research (De Ceuster & Degryse 2020). While graphical assessment of lead isotope ratios in bi-plots continues to be used in archaeological studies, kernel density estimates have been suggested as being more appropriate for data representation and for statistical calculations (Baxter et al 1997).…”

“…The lead isotope composition of the five artefacts in Table 2 was evaluated using a new numerical and graphical ‘match–no match’ method (De Ceuster & Degryse 2020). Kernel density estimates have so far been rarely applied in archaeological lead isotope studies (e.g.…”

Lead isotope analysis for provenancing ancient materials: a comparison of approaches

“…[11][12][13] This paper makes an in-depth comparison of three common methods used in assessing lead isotope data for archaeological provenancing purposes: the conventional bivariate plots, the cluster and model age method advocated by Albarède et al 1 and the KDE method proposed by De Ceuster and Degryse. 2 Each method will be applied on the data set of 99 silver coins as used in Albarède et al 11 The paper also aims to dene for each approach the advantages and disadvantages and to determine to what extent these methods contrast or complement one another.…”