Identification of Unnatural Subsets in Statistical Data

Benford's law is an observation on the frequency distribution of first significant digits in natural numerical data. We can measure the unnaturalness of the data by evaluating estrangement of the frequency distribution of leading digits of the data in relation to the Benford's distribution. However, we cannot identify the unnatural part of the data precisely. In this study, we focus on the fact that statistical data is generally provided in tabular form. We specify a subset of the target data by using the item names of rows and columns that define each cell of the table or words appearing in the table title. By measuring the degree of divergence of the subset from Benford's distribution, we can identify unnatural subsets. We apply this method to agriculture-related data from China Statistical Yearbook and succeeded to identify unnatural subsets.