手法を比較

	Nearest Neighbour Index	Scan Statistic Cluster Detection
分野	Human Geography	Human Geography
系統	Process / pipeline	Process / pipeline
提唱年	1954	1997
提唱者	Philip J. Clark & Francis C. Evans	Martin Kulldorff
種類	Summary statistic for the degree of clustering or dispersion in a point pattern	Hypothesis-testing method for detecting statistically significant spatial clusters
原典	Clark, P. J., & Evans, F. C. (1954). Distance to nearest neighbor as a measure of spatial relationships in populations. Ecology, 35(4), 445–453.	Kulldorff, M. (1997). A spatial scan statistic. Communications in Statistics – Theory and Methods, 26(6), 1481–1496.
別名	Clark-Evans Index, Nearest Neighbour Analysis, NNI	Kulldorff Scan Statistic, Spatial Scan Statistic, SaTScan Cluster Detection
関連	4	3
概要	The nearest neighbour index, introduced by Clark and Evans in 1954, is a simple summary statistic that quantifies whether a set of points is clustered, randomly scattered, or evenly dispersed across an area. It compares the average distance from each point to its closest neighbour with the average distance that would be expected if the same number of points were placed completely at random. The ratio of observed to expected distance, together with a significance test, gives a single interpretable number that has become a staple of point-pattern analysis in geography and ecology.	The spatial scan statistic, introduced by Martin Kulldorff in 1997, is a method for detecting and testing the significance of spatial clusters of events such as disease cases. It moves windows of many sizes and positions across the study region, treating each window as a candidate cluster, and scores it by a likelihood ratio comparing the rate of events inside the window to the rate outside. The window with the highest score is the most likely cluster, and its significance is assessed by Monte Carlo simulation, giving a principled answer to the recurring question of whether an apparent hotspot is real or chance.