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Table 5 Performance of predictive generalised linear models in Somalia for real-time estimation, by acute malnutrition outcome

From: Can we predict the burden of acute malnutrition in crisis-affected countries? Findings from Somalia and South Sudan

Statistic Categorical outcomes Continuous outcomes
SAM (WFH + oedema) GAM (WFH + oedema) SAM (MUAC + oedema) GAM (MUAC + oedema) WFH MUAC
Predictors: coefficient† on training data
Main local livelihood type
 Agriculturalists [ref.] [ref.] [ref.] [ref.] [ref.] [ref.]
 Displaced 0.61* 0.81* 0.44*** 0.45*** 0.144** 0.337***
 Pastoralists 0.80 0.90 0.37*** 0.48*** 0.105 0.294***
 Urban 0.66 0.76 0.62 0.68* 0.121 0.082
Incidence of armed conflict deaths    2-4mths prior 2-4mths prior   2-4mths prior
 0    [ref.] [ref.]   [ref.]
 0.1 to 4.9    1.574*** 1.81***   -0.291***
 ≥ 5.0    0.869 0.98   0.057
Terms of trade (cereals : wage)    4-6mths prior    
 < 30,000 Kcal    [ref.]    
 ≥ 30,000 Kcal    0.898    
Measles incidence rate previous 3mths previous 3mths     
 0 [ref.] [ref.]     
 > 0 1.44*** 1.34***     
Mean NDVI previous 6mths    previous 6mths previous 6mths  
 < 0.20 [ref.]    [ref.] [ref.]  
 ≥ 0.20 0.90    0.79** -0.009  
Mean price of 200L water   3-5mths prior   1-3mths prior 3-5mths prior 1-3mths prior
 < 20,000 SOS   [ref.]   [ref.] [ref.] [ref.]
 ≥ 20,000 SOS   1.23***   1.24* -0.161*** -0.229***
Estimation performance
Mean square error training data 0.00028 0.00248 0.00013 0.00177 0.05521 0.10219
LOOCV 0.00032 0.00345 0.00011 0.00186 0.06923 0.10682
holdout data 0.00015 0.00206 0.00007 0.00335 0.05765 0.11918
Relative bias LOOCV +35.6% +11.6% +91.4% +57.6% +12.3% -0.1%
holdout data +38.3% +27.2% +119.6% +59.7% +27.1% -0.3%
Relative precision of 95%CI LOOCV ±13.1% ±5.9% ±22.8% ±10.4% ±3.4% ±30.0%
holdout data ±13.7% ±6.2% ±24.7% ±11.2% ±3.8% ±30.0%
Coverage of 95%CI LOOCV 58.7% 48.9% 70.2% 45.7% 39.1% 42.6%
holdout data 80.0% 50.0% 80.0% 30.0% 40.0% 16.7%
Coverage of 80%CI LOOCV 39.1% 38.3% 44.7% 37.0% 23.9% 25.5%
holdout data 50.0% 36.7% 43.3% 23.3% 26.7% 16.7%
Classification performance by SAM/GAM prevalence threshold (n = denominator of percentage)
Sensitivity, lower threshold LOOCV ≥2% 100.0%
(40)
≥15% 79.2%
(24)
≥2% 50.0%
(18)
≥15% 25.0%
(4)
n/a
holdout data 100.0%
(25)
83.3%
(12)
50.0%
(4)
0.0%
(3)
Sensitivity, upper threshold LOOCV ≥5% 33.3%
(9)
≥20% 12.5%
(8)
≥5% 0.0%
(1)
≥20% 0.0%
(2)
holdout data 50.0%
(2)
33.3%
(3)
n/a
(0)
0.0%
(1)
Specificity, lower threshold LOOCV <2% 0.0%
(6)
<15% 34.8%
(23)
<2% 82.8%
(29)
<15% 97.6%
(42)
holdout data 0.0%
(5)
27.8%
(18)
76.9%
(26)
96.3%
(27)
Specificity, upper threshold LOOCV <5% 89.2%
(37)
<20% 89.7%
(39)
<5% 97.8%
(46)
<20% 97.7%
(44)
holdout data 96.4%
(28)
96.3%
(27)
100.0%
(30)
100.0%
(29)
  1. †Odds ratio for categorical outcomes; linear coefficient for continuous outcomes
  2. *0.01 ≤ p-value < 0.05 ** 0.001 ≤ p-value < 0.01 *** p-value < 0.001