Measuring inequality: The effect of units of analysis on the Gini coefficient

To variable degrees, inequality is present in all human societies, but how archaeologists measure inequality varies greatly. In recent research, we used the same unit of analysis, house size, to evaluate residential wealth inequality among the Classic (a.d. 250/300–800) Maya of southern Belize. Using a Gini coefficient, we found that even in this peripheral region, high degrees of inequality were present. However, nuances in inequality metrics vary based on the analytical parameters or units of measurement (area versus volume) and the unit of analysis (individual residential structures, all structures within a household group, or the entire household group, including the built environment). Generally, Gini coefficients calculated from volume are greater than those from area, and the unit of analysis affects the Gini coefficient and, thus, our interpretations of the degree of inequality present. We discuss the impact of the unit of analysis for house sizes, and how it affects our interpretations of residential wealth inequality in the past in conjunction with previous archaeological research. The findings are instrumental for comparative analyses of wealth inequality through the study of house size variation in ancient and modern societies, highlighting the value of clear definitions of the unit of analysis.