PLANT-DISEASE INCIDENCE - DISTRIBUTION, HETEROGENEITY, AND TEMPORAL ANALYSIS

The statistical properties of disease incidence are reviewed and used to characterize spatial patterns of diseased entities (e.g. plants), s atisfy assumptions of statistical analyses, and quantify change in inc idence over time. Frequency of diseased plants can be represented by t he binomial or, more commonly, the beta-binomial distribution. Spatial patterns of disease can be described by the aggregation parameter of the beta-binomial distribution, index of dispersion and related statis tics, parameters of the binary form of the power law, as well as measu res of spatial autocorrelation between sampling units. Disease inciden ce over time can be represented by continuous- and discrete-time nonli near disease progress models, such as the logistic, and by autoregress ive, integrated, moving average models. Ultimately, simultaneous spati o-temporal analyses can be performed to understand the dynamics of dis ease incidence in populations.