The Archaeological Utility of ACTUS: An Alternative Method of Contingency Table Analysis Using Simulation

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Archaeologists rely heavily on contingency table analyses of count data to infer relationships between variables and proportional differences between populations. For example, archaeologists often use contingency table analyses of sample data to make inferences about inter-site variation in lithic raw material type proportions. The most common methods for making these inferences are the Chi-Square test and Fisher's Exact test. However, the former cannot be applied to small samples and the latter cannot be applied to tables larger than 2x2. Consequently, many archaeological studies rely only on sample proportions to draw conclusions about population proportions. We suggest an alternative approach using ACTUS (Analysis of Contingency Tables Using Simulation), a computationally intense simulation program developed by George Estabrook and used mainly in biology. Compared to traditional methods, ACTUS offers four advantages: it enables rigorous statistical inferences despite low counts; it generates probability values for each individual cell, aiding interpretation of probability values generated for the entire table; even the least quantitatively oriented archaeologist can understand how the program works; and the free software operates rapidly, producing results based on thousands of simulated tables in just seconds. Here we explain the method and use several archaeological examples to demonstrate its utility.


Society for American Archaeology annual meeting


Orlando, FL