The effect of raw material on inter-analyst variation and analyst accuracy for lithic analysis: a case study from Olduvai Gorge Tomos Proffitt * , Ignacio de la Torre Institute of Archaeology, University College London, 31-34 Gordon Square, WC1H 0PY London, United Kingdom article info Article history: Received 21 November 2013 Received in revised form 29 January 2014 Accepted 25 February 2014 Available online 12 March 2014 Keywords: Lithic technology Olduvai Gorge Blind tests Inter-analyst variability Analyst accuracy Refit analysis abstract This study aims to understand what effect, in terms of inter-analysis variation and analyst accuracy, different raw material types have on modern technological analyses of lithic assemblages. This is done through a series of blind analysis tests undertaken on experimentally derived assemblages of cores and flakes. Novelties of our approach include the introduction of refit studies as a method to assess analyst’s accuracy, and the use of statistical tests specifically designed to address inter-analyst variability, common in other disciplines but rarely used in Archaeology. The experimental assemblages were produced from raw materials collected at Olduvai Gorge, an archaeological sequence that has been a source for studies of early human technology for several decades, and where re-analyses of the same assemblages have usually offered different interpretations. The results of the blind analyses are compared to the true technological values obtained through full refit analysis of the experimental material, and suggest that there is a significant difference in terms of inter-analyst variability as well as accuracy related to different raw materials. Our paper highlights the interpretative problems posed by difficult-to-analyse raw ma- terials such as quartzite, and stresses subjectivity present in stone-tool technological studies, which may contribute to explain differences in the interpretation of Early Stone Age lithic assemblages. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Since Mary Leakey’s (1971) seminal work, the importance of the Olduvai assemblages as a continued source of archaeological data and interpretations regarding technological skill (de la Torre and Mora, 2005), manual dexterity, cognitive evolution (Ludwig, 1999), wider landscape use (Potts, 1988; Blumenschine et al., 2008) and raw material procurement (Kimura, 1997, 1999, 2002; Kyara, 1999) has been made clear. It is noticeable, however, that from the same assemblages different results and varying (some- times contradictory) interpretations are produced by different re- searchers (see review by de la Torre and Mora, 2009). The implementation of lithic technological studies requires the correct identification of numerous common technological charac- teristics and markers located on lithic material. Nonetheless, to date surprisingly few studies have attempted to identify the level of inter-analyst accuracy associated with the identification of tech- nological characteristics of lithic assemblages. At a general level, studies investigating inter-analyst variability have concentrated on the identification of variability caused by random and systematic error of the analyst (Gnaden and Holdaway, 2000), of typological identification between analysts and by individual analysts over time (Beck and Jones, 1989; Fish, 1978; Whittaker et al., 1998), the correctness of lithic measurements (Fish, 1978) and cortex coverage (Fish, 1978). In terms of identifying analyst accuracy on assemblages made up of a single raw material type, Driscoll (2011), Jeske and Lurie (1993), and Perpère (1986) conducted blind tests based on a tech- nological approach. Driscoll (2011) investigated how the correct- ness of a number of analysts of varying skill level was affected by quartz. Jeske and Lurie (1993) conducted blind tests in order to identify attributes which would distinguish bipolar knapping from freehand knapping, and Perpère (1986) used three lithic analysts to identify Levallois and non-Levallois flakes from an archaeological assemblage. More generally, blind analyses have been implemented to assess the level of inter-analyst correctness in the identification of bone modification on faunal remains (e.g. Blumenschine et al., 1996; Gobalet, 2001), and the identification and quantification of use wear patterns within lithic residue and microwear analysis (Newcomer et al., 1986; Wadley et al., 2004; Rots et al., 2006; Crowther and Haslam, 2007). Nonetheless, to date no studies * Corresponding author. Tel.: þ44 7889 369 826. E-mail address: t.proffitt@ucl.ac.uk (T. Proffitt). Contents lists available at ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas http://dx.doi.org/10.1016/j.jas.2014.02.028 0305-4403/Ó 2014 Elsevier Ltd. All rights reserved. Journal of Archaeological Science 45 (2014) 270e283