Statistics for Describing Populations
Although evaluating dispersion may be challenging, knowledge of spatial patterns provides information vital to understanding basic behavior of a species. The variance-to-mean ratio is the simplest, most fundamental index and is useful for assessing agreement of the data set to the Poisson series. Reasoning that the diversity of numbers of individuals per quadrat could be used as a measure of spatial pattern, Morisita developed the index Iδ. Geostatistics relies on spatial variation to determine the degree of association and dependence of spatially related data. Recently, D. J. Schotzko and L. E. O'Keeffe evaluated dispersion of Lygus hesperus Knight in lentils with geostatistics and evaluated the effect of sample unit size and sample placement on geostatistical analysis. Evaluating insect spatial patterns with geostatistics requires intensive sampling of the specified area. Schotzko and O'Keeffe point out several limitations of using geostatistics for assessing insect dispersion.