Fig. 7. The under- or over-estimation of pH and lime requirement (LR) following map development based on area composite (AC), point (P) or centers point (CP) sampling strategies for NEPAC. Composite strategies include a research whole field (AC WF, all samples averaged), a commercial or true farm whole field (AC TF, subsets of samples representing a density of 1 ha^–1 averaged), and 1-ha grid (AC 1 ha, all samples averaged on a ha^–1 basis). Maps developed from point data use either the CP value of a given ha to represent the whole ha without any smoothing (No. Smth CP_1ha), ID_P=2 applied to CP 1 ha data, or kriging applied to CP 0.1 and P 0.4 ha data. Box plots show error mean (...), median (—), 25th to 75th percentiles (), 10th and 90th percentiles (,), and 5th and 95th percentiles (•). A cross () next to the AC TF mean absolute error (MAE) indicates µ_{AC TF} 0 (p < 0.05). Underlined MAEs of other strategies indicates µ_other µ_{AC TF} (p < 0.05). All prediction efficiencies (PE) are calculated relative to AC TF, and underlined PEs indicate _{other TF} (p < 0.05).