Figure 4

Model fitting and cross validation using GWR and the LME model (N = 162,089). RMSE: root mean squared error of the predictions (µg/m3). For reference, the 1:1 line is shown as a dashed line. Panels (a) and (b) show the model fitting and cross-validation results of the GWR model, whereas panels (c) and (d) show the model fitting and cross-validation results of the LME model, respectively.