The FHTET Invasive Species Sample Design Tool prioritizes the selection of sample locations for detection and survey activities based on pest risk. Sample location selection is conducted in ArcGIS 10.0 using the "Create Spatially Balanced Sample" tool which generates spatially balanced sample points based on the inclusion probability surface. The spatially balanced design improves sampling efficiency by maximizing the spatial independence of sample points, thereby providing the most information available per sample unit.
Benefits of the tool are that users may dynamically set the geographic area of interest and specify the number of sample locations to be selected. To create the sample points, the tool requires two inputs, 1) an inclusion probability raster, and 2) the number of output sample locations specified by the user. The tool then automates the selection of spatially balanced sample locations from a standardized 1 km grid for the contiguous U.S. using a risk based inclusion probability surface. By utilizing a surface with known inclusion probabilities, the tool provides an objective and transparent methodology for selecting sample locations.