Will the Real Hopkins Statistic Please Stand Up?

Abstract

Hopkins statistic (Hopkins and Skellam 1954) can be used to test for spatial randomness of data and for detecting clusters in data. Although the method is nearly 70 years old, there is persistent confusion regarding the definition and calculation of the statistic. We investigate the confusion and its possible origin. Using the most general definition of Hopkins statistic, we perform a small simulation to verify its distributional properties, provide a visualization of how the statistic is calculated, and provide a fast R function to correctly calculate the statistic. Finally, we propose a protocol of five questions to guide the use of Hopkins statistic