Figure 4: Boxplots of the 100 RMSE of the models predicting stagnic layer thickness. (a) 10 m terrain resolution, (b) 20 m terrain resolution, and (c) 30 m terrain resolution. 1 = default Random Forest parameters, 2 = additional predictor selection, 3 = 1, 2+ tuning of sampsize, and 4 = 1, 2+ tuning of mtry. The lines refer to the boxplot parameters of the RMSE distribution of the mean of the data as prediction model. Solid line: median, dashed line: upper/lower hinges, and dotted line: upper/lower whiskers.