Online Resource 2 - Error analysis

Online resource 2 compares the population exposures calculated from modelling with those calculated from radii in terms of their mean percentage error (MPE) and Chi-square error, which are two order-dependent error functions. This gives us information about the dispersion around the 1:1 modelled:radii line. The MPE provides a proportional deviation from the model’s mean prediction but results in larger penalties for overestimations. For instance, negative MPE values (i.e., when the exposure of footprints is lower than buffers) are bounded to -100%, whereas positive MPE values have no upper limit. In contrast, the Chi-square provides a more symmetrical error.