Inferring Alignments I

Exploring the Accuracy and Precision of Two Statistical Approaches


  • Fabio Silva Institut Català de Paleoecologia Humana i Evolució Social (IPHES, Spain) and University of Wales Trinity Saint David (UK).



accuracy, curvigram, inference, likelihood, precision, statistics


Using computer simulations, this paper explores and quantifies the accuracy and precision of two approaches to the statistical inference of the most likely targets of a set of structural orientations. It discusses the curvigram method (also known as kernel density estimation or summed probability distribution) in wide currency in archaeoastronomy, and introduces the largely unutilised maximum likelihood (ML) method, which has popularity in other academic fields. An analysis of both methods’ accuracy and precision is done, using a scenario with a single target, and the resulting equations can be used to estimate the minimum number of surveyed structures required to ensure a high-precision statistical inference. Two fundamental observations emerge: firstly, that although both approaches are quite accurate, the ML approach is considerably more precise than the curvigram approach; and secondly, that underestimating measurement uncertainty severely undermines the precision of the curvigram method. Finally, the implications of these observations for past, present and future archaeoastronomical research are discussed.


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Author Biography

Fabio Silva, Institut Català de Paleoecologia Humana i Evolució Social (IPHES, Spain) and University of Wales Trinity Saint David (UK).

Fabio Silva is currently a Marie-Skłodowska-Curie Fellow at the Instititut Català de Paleoecologia Humana i Evolució Social (IPHES) in Spain and a tutor in the Sophia Centre for the Study of Cosmology in Culture (University of Wales Trinity Saint David, UK), where he is responsible for a postgraduate taught module titled 'Skyscapes, Cosmology and Archaeology'. His current research interests focus on how humans perceive their environment (skyscape and landscape) and use that knowledge to time and adjust their social and productive behaviours. His archaeoastronomical research has mostly focused on Neolithic Portugal, though he has also done fieldwork in the United Kingdom and Malta. His books include "Skyscapes: The Role and Importance of the Sky in Archaeology" (edited with Nick Campion, Oxbow Books, 2015). He has received the Fifth Carlos Jaschek Award from the European Society for Astronomy in Culture (SEAC) in 2016.


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How to Cite

Silva, F. (2017). Inferring Alignments I: Exploring the Accuracy and Precision of Two Statistical Approaches. Journal of Skyscape Archaeology, 3(1), 93–111.



Theory & Method