STATISTICAL APPROACH FOR EQUIVALENT DOSE DETERMINATION IN HISTORICAL MORTARS DATING

A methodological study aimed to evaluate the bleaching degree of quartz fractions extracted from historical mortars is presented. Equivalent Dose (ED) measurements on small aliquots of two different quartz fraction, inclusion (90 μm<150 μm) and coarse grain (180 μm<212 μm), were performed by optically stimulated luminescence using single aliquot regeneration procedure. In order to choose the more suitable age model to be used, the bleaching degree was studied through a deep statistical approach using ED frequency distribution, Q-Q plot and Shapiro-Wilk normality test. The results show that ED from coarse grain could be statistically associated to normal distribution and then Central Age Model (CAM) can be used for Archaelogical dose calculation. The quartz inclusion data don’t follow a normal distribution and then Minimum Age Model (MAM) is more appropriate. Archaelogical dose results obtained in two different age models were in good agreement.