Skip to main content

Table 3 Summary output of Bayesian geostatistical models for the north and south of Somalia.

From: Spatial prediction of Plasmodium falciparum prevalence in Somalia

Model/Variables North South
Bayesian geostatistical model (no covariates)   
α (Intercept) -4.62 (-5.44, -4.33) -2.9 (-3.37, -2.27)
ϕ (Decay of spatial correlation (degrees latitude and longitude)) 8.90 (3.11, 12.75) 4.79 (2.11, 6.97)
σ2 (Variance of spatial process) 4.35 (271, 7.14) 7.14 (5.00, 8.76)
DIC 326 1,454
ME (% Pf PR) 3.83 4.14
MAE (% Pf PR) 4.12 5.06
AU-ROC*   
   <5% Pf PR 0.72 (0.64, 0.86) 0.87 (0.72, 0.91)
   5–39% Pf PR 0.66 (0.51, 0.80) 0.78 (0.66, 0.85)
   ≥ 40% Pf PR NA 0.56 (0.37, 0.73)
Bayesian geostatistical model (with covariates)   
α (Intercept) -4.62 (-5.23, -4.10) -2.86 (-3.79, 2.27)
ϕ (Decay of spatial correlation) 10.35 (4.70, 12.88) 5.78 (2.95, 6.99)
σ2 (Variance of spatial process) 3.70 (2.17, 7.14) 5.00 (3.70, 6.70)
DIC 323 1,429
ME (% Pf PR) 2.56 3.65
MAE (% Pf PR) 4.75 5.00
AU-ROC*   
   <5% Pf PR 0.75 (0.64, 0.91) 0.91 (0.87, 0.99)
   5–39% Pf PR 0.64 (0.43, 0.84) 0.81 (0.70, 0.94)
   ≥ 40% Pf PR NA 0.51 (0.32, 0.83)
  Odds ratio, (95% Bayes credible interval)
Month of survey   
   Feb Ref Ref
   Mar - 4.06 (2.20, 7.63)
   Jun -  
   Jul 3.25 (0.91, 11.36) 0.87 (0.48,1.46)
   Sep 0.2 (0.02, 1.74)  
   Nov 1.31 (0.33, 4.36) 0.48 (0.23, 0.96)
   Dec - 1.95 (0.91, 3.90)
Annual average minimum temperature   
   <median of 20.4/22.1 (North/South)°C Ref -
   >median of 20.4/22.1(North/South)°C 1.12 (0.84, 1.33) 0.83 (0.67,0.96)
Annual average precipitation 1.70(0.53, 5.44) 1.41 (1.07, 1.94)
Distance to water features (km) 1.22 (0.53, 2.81) 0.79 (0.74, 1.29)
  1. DIC = deviance information criterion (measure of model fit); ME = mean error (measure of overall bias); MAE = mean absolute error (measure of overall precision); AU-ROC = areas under receiver operating characteristic. Values in parentheses are 95% Bayes credible intervals.
  2. *There were only two survey locations in the validation set that had Pf PR ≥ 40% in the north region meaning reliable AU-ROC values could not be computed for this model.