2DCLASS, a Two-Dimensional Distance Class Analysis Software for the Personal Computer. Scot C. Nelson, Department of Plant Pathology, North Carolina State University, Raleigh 27695. Paul L. Marsh, and C. Lee Campbell. Department of Statistics, and Department of Plant Pathology, North Carolina State University, Raleigh 27695. Plant Dis. 76:427-432. Accepted for publication 6 January 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0427.

2DCLASS is microcomputer software capable of performing Gray’s two-dimensional distance class analysis of spatial pattern of plant disease. The program allows for rapid and concise analysis of the spatial pattern of binomial (presence/absence) data within a two-dimensional matrix (e.g., rows and columns of plants). The procedure is particularly useful for the detection and quantification of nonrandom spatial patterns, average cluster size, distance between or among clusters, relative cluster location within a lattice, within-row and across-row aggregation, and edge effects. The software also generates a map of observed spatial pattern and is tolerant of missing data points. Instructions (with examples) for use of 2DCLASS and guidelines and cautions for interpretation of program output are provided.