Table 3.
Effects of categorical variables as percent increase or decrease of the mean HAN:THM ratio; interactions of groundwater with season and disinfectant sequence.
| Explanatory variables | Percent effect (2.5%, 97.5% CI) | Adjusted mean ratio | Sig. |
|---|---|---|---|
| GW, FINISH, Summer, CL2-CL2 | 165 (122, 217) | 0.315 | ∗∗∗ |
| Season (GW, FINISH, CL2-CL2) | |||
| Autumn | −11.0 (−15.8, −5.8) | 0.313 | ∗∗∗ |
| Winter | −26.6 (−31.3, −21.7) | 0.319 | ∗∗∗ |
| Spring | −14.3 (−19.9, −8.4) | 0.323 | ∗∗∗ |
| Disinfectant sequence (GW, FINISH, Summer) | |||
| CL2-CLM | 21.0 (−58.8, 255) | ||
| Cl2-CLM-CLM | −27.8 (−46.3, −3.0) | 0.271 | ∗ |
| CLM | −22.0 (−45.0, 10.6) | ||
| CL2 | 39.5 (−1.4, 97.4) | 0.421 | . |
| O3-CLM | −34.5 (−78.0, 94.7) | ||
Table key: Sig.: significance to the ∗95% confidence level, ∗∗99% confidence level, and ∗∗∗>99.9% confidence level (”.” indicates near significance at the 95% confidence level).
Table notes: Values for adjusted mean ratios are only provided if the effect was significant. Effect estimates from Table S5B are converted to percentages by exponentiating, subtracting one, and multiplying by 100. To calculate the adjusted mean ratio for a category with groundwater, refer to Table 2 for the adjusted mean ratio of that category with surface water, multiply by 265% (the percent effect for groundwater plus 100%), and finally multiply by the percent effect of that category with groundwater plus 100%.