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Table 3 Models imputing outcome variables

From: Heckman-type selection models to obtain unbiased estimates with missing measures outcome: theoretical considerations and an application to missing birth weight data

Outcome variableBirth weight in grams
VariableImputationPIDA
Mean imputationMICEGroup Mean replacementa-0.5SDb+ 0.5SDc
 IFAS: No
 Yes7.02 (−13.97; 28.01)22.38 (−13.49; 58.26)18.71* (−2.27; 39.69)−51.78*** (−73.76; − 29.80)76.78*** (54.99; 98.57)
Educational attainment: No schooling(+)
 Primary10.96 (−9.75; 31.66)20.03 (− 12.71; 52.77)10.98 (−9.72; 31.68)13.73 (− 7.96; 35.41)7.98 (− 13.52; 29.48)
 Coranic22.96 (− 19.61; 65.52)36.12 (− 26.93; 99.17)23.34 (−19.22; 65.89)36.71 (− 7.87; 81.29)8.31 (−35.88; 52.51)
 Secondary or higher32.13* (−0.03; 64.30)49.47** (0.90; 98.03)32.09* (− 0.06; 64.25)45.41*** (11.72; 79.09)17.79 (− 15.61; 51.18)
Maternal age (years): 20–34(+)
 15–19− 133.30*** (− 160.60; − 106.00)−209.30*** (− 253.10; − 165.50)−133.92*** (− 161.23; − 106.61)−131.68*** (− 160.29; −103.07)− 135.34*** (− 163.71; − 106.98)
 35–499.22 (− 19.01; 37.44)6.91 (− 36.48; 50.30)9.46 (−18.76;- 37.67)24.99* (− 4.57; 54.54)− 7.68 (− 36.98; 21.62)
Socioeconomic status: Most poor(+)
 Poor14.68 (−14.16; 43.52)32.48 (− 18.42; 83.39)14.43 (− 14.40; 43.27)21.87 (−8.33; 52.07)6.79 (− 23.16; 36.74)
 Middle13.04 (− 17.00; 43.08)25.15 (− 24.63; 74.93)12.77 (− 17.26; 42.79)42.02*** (10.57; 73.48)− 18.40 (− 49.58; 12.79)
 Rich−1.75 (− 31.22; 27.71)− 0.52 (− 53.46; 52.41)−1.93 (− 31.39; 27.52)27.05* (− 3.81; 57.91)− 32.94** (− 63.54; -2.35)
 Most rich35.31* (− 0.68; 71.30)53.72* (− 4.44; 111.90)35.06* (− 0.92; 71.03)66.49*** (28.80; 104.18)1.52 (− 35.84; 38.89)
Child sex: Male(+)
 Female− 80.03*** (− 97.96; − 62.09)− 125.20*** (− 153.80; − 96.59)− 80.17*** (− 98.10; − 62.24)− 80.28*** (− 99.06; − 61.50)−79.83*** (− 98.45; − 61.21)
Previous births: 0 child(+)
 1–444.13* (− 2.89; 91.15)57.12 (− 17.29; 131.50)44.35* (− 2.65;- 91.35)40.49 (− 8.75; 89.73)48.18* (− 0.64; 96.10)
 ≥5112.30*** (59.65; 164.90)186.30*** (100.60;- 272.00)112.38*** (59.77; 165.00)94.30*** (39.17; 149.43)131.75*** (77.10; 186.40)
Twin births: No(+)
Yes− 476.80*** (−518.80; − 434.80)− 642.10*** (− 702.90; − 581.40)−476.64*** (− 518.62; − 434.66)− 452.14*** (39.18; 149.42)− 503.37*** (− 546.98; − 459.78)
observations73257325732573257325
  1. MICE Multiple imputations by chained equation. MICE was done with 150 imputations using Stata mi estimate package
  2. PIDA Pattern imputation with delta adjustment
  3. aMissing values were replaced with mean of group (mean of observed birth weight for treated, and mean of observed birth weight for non-treated for control)
  4. bMissing values were replaced with a birth weight half a standard deviation lower than the observed mean.
  5. cMissing values were replaced with a birth weight half a standard deviation above the observed mean.
  6. *** p < 0.01. ** p < 0.05.* p < 0.1;(+) Reference category; Adjusted model controls village fixed effects; CI: confidence interval