Application of Generalized Linear Regression to Understand the Use-wear Patterns of Stone Tools made on Shahabad

Debanjan Mitra (Deccan College Post Graduate Research Institute, Pune, India)

Limestone has been an important raw-material for stone tool manufacturing in India, especially in Hunsgi – Baichbal Valley, Karnataka, which reports an elaborate Acheulian workshop. Recently, the author has taken up a project to create a parametric catalogue to study the functional traces on the tools made on Shahabad limestone. Six categories of variables were considered which determined the edge-damage patterns due to use which include activity, edge-angle (θ) of the employed unit, length of employed unit, aspect, raw-material and time. The values of the dependent variables were classified into eighteen categories which were meticulously recorded for the hundred and four experimental specimens creating a huge pool of quantitative data bank. As all the six variables were acting simultaneously to create the damage, it became necessary to establish the correlation between the determinants to form edge damages, so that it standardise the edge-damage patterns in relation to the variability of the determinants.

The basic structure of the data universe has eighteen classified dependent variables and six independent variables. In such a model where multiple independent variables were determining the edge-damages, Generalized Linear Regression Model was adopted to establish the co-relationship. Specifically, Poisson Generalized Linear method was applied as it assumes the response variable has a Poisson distribution and assumes the logarithm of its expected values which can be modeled by a linear combination of unknown parameters. The application of this method have successfully produced a detailed statistical analysis and interpretation of the co-relationship between the multiple set of dependent and independent variables to form the edge-damage patterns and have also verified the null hypotheses. This statistical application has significantly helped to develop a parametric catalogue for analysing the functional traces on prehistoric tools made on Shahabad limestone.

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