Classification and unscrambling a classinside-class situation by object target rotation: Hungarian silver coins of the Arpad Dynasty, AD 997–1301

摘要

Classification is an important part of chemometrics and mostly based on optimization by vector rotations. The present study is a continuation of the classification of medieval Hungarian silver coins including the 16 kings of the Hungarian arpad Dynasty (AD 997–1301) (Racz et al.: Heritage Science 2013 1:2). The Racz et al. paper identified three historical periods of the arpad Dynasty from chemical data. The aim of the present study is to test whether the classification could be further refined by marker object projection-aided classification. It offers an example of the efficiency of this method in unscrambling a class-inside-class situation. The frequency distribution of concentrations of the coins is skewed and to a certain extent bimodal, and the arithmetic mean value and standard deviation around the mean frequently used in parametric methods may be poor descriptors of the information carried by the data. We test a combination of principal component decomposition and the nonparametric, noniterative object target rotationmethod to overcome some of the theoretical limitations of parametric methods. This test includes identification of archetypical class “Ambassadors” of each of the three historical periods of the arpad Dynasty and shows a class-inside-class situation.