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A random variable is a mathematical function that translates a construct into numbers that behave in some random way. A space-time stochastic process is a mathematical function that yields a time-series random variable for each location on a map. A geographic distribution is a map (e.g., a GIS layer) taken from some space-time stochastic process. Each of its location-specific variables possesses statistical quantities, such as measures of central tendency and dispersion. When a map for only a single point in time is observed, these statistical properties often are assumed to be constant across all locations. In contrast, spatial nonstationarity means statistical parameters of interest are dependent upon and unstable across location. Most spatial statistical techniques require data to be either stationary or modified in some ...

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