Table 1.

Variable coefficients of the multilinear model with R² value of 0.44 and P value of 4.4 × 10⁻⁸

Variable in model	Variable coefficient
Intercept	2.84*
D	0.00039
C = coal area	−5.50***
P = unplugged	3.99***
P = plugged/vented	8.33***
W = oil	−2.88*
$r_S$	0.016
$r_U$	−0.087

These results are for model L6b in SI Appendix, Table S3. The results of additional models are shown and discussed in SI Appendix. P values are noted (*P < 0.05; ***P < 0.001).