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Table 3

Intervention effect sizes for quasi-Poisson and ordinal logistic regression models with intention-to-treat and per-protocol analysis

Quasi-Poisson models
AnalysisUnadjustedAdjusted – all but source water qualityAdjusted – source water quality onlyFully adjusted
Intention-to-treat −0.42 (−0.46, −0.38) −0.39 (−0.43, −0.35) −0.29 (−0.33, −0.26) −0.23 (−0.59, 0.13) 
Per-protocol −0.56 (−0.60, −0.52) −0.55 (−0.59, −0.51) −0.44 (−0.48, −0.41) −0.44 (−0.48, −0.40) 
Ordinal logistic models
AnalysisUnadjustedAdjusted – all but source water qualityAdjusted – source water quality onlyFully adjusted
Intention-to-treat −1.03 (−1.50, −0.56) −0.95 (−1.42, −0.48) −0.74 (−1.21, −0.26) −0.69 (−1.17, −0.21) 
Per-protocol −1.42 (−1.91, −0.93) −1.36 (−1.85, −0.86) −1.14 (−1.64, −0.64) −1.11 (−1.61, −0.61) 
Quasi-Poisson models
AnalysisUnadjustedAdjusted – all but source water qualityAdjusted – source water quality onlyFully adjusted
Intention-to-treat −0.42 (−0.46, −0.38) −0.39 (−0.43, −0.35) −0.29 (−0.33, −0.26) −0.23 (−0.59, 0.13) 
Per-protocol −0.56 (−0.60, −0.52) −0.55 (−0.59, −0.51) −0.44 (−0.48, −0.41) −0.44 (−0.48, −0.40) 
Ordinal logistic models
AnalysisUnadjustedAdjusted – all but source water qualityAdjusted – source water quality onlyFully adjusted
Intention-to-treat −1.03 (−1.50, −0.56) −0.95 (−1.42, −0.48) −0.74 (−1.21, −0.26) −0.69 (−1.17, −0.21) 
Per-protocol −1.42 (−1.91, −0.93) −1.36 (−1.85, −0.86) −1.14 (−1.64, −0.64) −1.11 (−1.61, −0.61) 

Effect sizes represent coefficients for time × treatment interaction with 95% confidence intervals indicated in parentheses. Quasi-Poisson model coefficients represent the log reduction in E. coli count, and ordinal logistic model coefficients represent the change in the log-odds of moving to the next lowest contamination level (e.g., a shift from 10– < 100 MPN/100 mL to 1– < 10 MPN/100 mL). Models adjusted for all variables except source water quality were adjusted for point-of-use water treatment, soap presence, open defecation, and rainfall. Fully adjusted models were adjusted for all of the above plus source water quality.

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