“…In the past decades, many other geostatistical objective functions have been proposed as an alternative to the kriging variance for optimal sampling design, such as the weighted kriging variance [26][27][28], interpolation variance [29][30][31], combined variance [31][32][33], conditional variance [34], information entropy [31,35], value of information [36], efficacy of information [37], GET (grade-estimation error-thickness) function [10,38], cross-validation error [39], interquartile range [40], probability interval widths [34,41], probability of classification error [42], probability of threshold exceedance [43], expected ore value [44], expected cost of classification errors [45], or increase of indicated and measured mineral resource categories [46]. These objective functions account for local ore grade variability, expected grade, expected productivity, expected profit, and/or reduction of uncertainty, unlike the kriging variance that only depends on the spatial correlation (variogram) and geometric configuration of the data.…”