. 2018 Mar 22;15(4):571. doi: 10.3390/ijerph15040571

Table 3.

Fitted binomial regressions of lgCr to depth (d) in the form of y = ax² + bx + c).

Binomial Type	Positive Binomial Distribution (n = 29)	Negative Binomial Distribution (n = 22)
a	0.016 ± 0.012	−0.007 ± 0.006
b	−0.268 ± 0.133	0.032 ± 0.085
c	3.973 ± 0.597	3.862 ± 0.467
( $- \frac{b}{2 a}$ , $- \frac{4 a c - b^{2}}{4 a}$ )	(8.4 ± 2.2, 2.7 ± 0.4)	(−2.0 ± 4.4, 4.1 ± 0.4)
equations	lgCr = 0.013 × d² − 0.026 × d + 3.805	lgCr = −0.006 × d² + 0.027 × d + 3.829
R²	0.218	0.208
p	<0.001	<0.001

Chromium concentration in soil was lg-transformed to ensure homogeneity of variances.