Table 3.

Predictors of iron concentration in tubewell water and residual-free chlorine in treated water

	Co-efficient	95% confidence interval	P value
Factors affecting iron concentration*
Tubewell depth (feet)	−0.002	−0.003, −0.001	< 0.001
Tubewell location (subdistrict)	0.074	0.035, 0.114	< 0.001
Year round presence of water in the tube well†	0.164	−0.130, 0.457	0.274
Factors affecting residual-free chlorine*
Tubewell water iron concentration (mg/L)	−0.299	−0.332, −0.265	< 0.001

^*Quantile regression models.

^†Binary variable (yes/no).