# Table 4 Sunshine duration-based seasonal regression models and their statistical evaluation

Model no. Model type Seasons Equations $$R^{2}$$ MBE MPE RMSE MARE t stat
7 Linear Summer (February–September) $$H/H_0 = 0.5077(S/S_0) + 0.1915$$ 0.96833 0.00131 0.09172 0.12833 0.02795 0.03394
Winter (October–January) $$H/H_0 = 0.8805(S/S_0) - 0.1174$$
8 Quadratic Summer (February–September) $$H/H_0 = 0.5469(S/S_0)^2 - 0.0692(S/S_0) + 0.3315$$ 0.97693 0.0023 0.05783 0.10953 0.02242 0.06984
Winter (October–January) $$H/H_0 = 9.3987(S/S_0)^2 - 11.518(S/S_0) + 3.9476$$
9 Third degree Summer (February–September) $$H/H_0 = -1.6819(S/S_0)^3 + 3.2167(S/S_0)^2 - 1.4324(S/S_0) + 0.5545$$ 0.98538 −0.00178 0.09116 0.08719 0.01302 0.06798
Winter (October–January) $$H/H_0 = 1290(S/S_0)^3 - 2585.5(S/S_0)^2 + 1723.8(S/S_0) - 381.77$$
10 Exponential Summer (February–September) $$H/H_0 = 0.2523\exp [1.1088(S/S_0)]$$ 0.97284 0.00425 0.04336 0.11886 0.02535 0.11858
Winter (October–January) $$H/H_0 = 0.1341\exp [1.8733(S/S_0)]$$
11 Logarithmic Summer (February–September) $$H/H_0 = 0.254\hbox {ln}(S/S_0) + 0.6323$$ 0.95165 −0.00049 0.1278 0.1586 0.03468 0.01023
Winter (October–January) $$H/H_0 = 0.5763\hbox {ln}(S/S_0) + 0.705$$
12 Power Summer (February–September) $$H/H_0 = 0.6617(S/S_0)^{0.5567}$$ 0.96336 0.00293 0.05992 0.13805 0.029 0.07044
Winter (October–January) $$H/H_0 = 0.7715(S/S_0)^{1.227}$$ 