Table 1: Summary statistics of covariates used in the stochastic frontier model and SLX models
Variables
|
Mean
|
SD*
|
Min
|
Max
|
Inputs for Teff production
|
Yield (ton ha-1)
|
1.21
|
0.27
|
0.64
|
2.05
|
Land (ha.)
|
1.24
|
0.75
|
0.20
|
3.50
|
Seed (kg ha-1)
|
30.77
|
9.58
|
10.86
|
50.99
|
Fertilizer (kg ha-1)
|
86.29
|
82.94
|
0
|
312.70
|
Labor (Man Day ha-1)
|
154.81
|
77.20
|
40.26
|
399.15
|
Oxen (number)
|
2
|
0.80
|
1
|
4
|
Sources of technical inefficiency
|
- Farmers’ own characteristics
|
Gender ( = 1 if the household is male-headed)
|
0.87
|
0.34
|
0
|
1
|
Education of the household head (years of schooling)
|
2
|
2.95
|
0
|
13
|
Participation in extension service program (= 1 if they participated)
|
0.56
|
0.49
|
0
|
1
|
Community participation (= 1 if they participated)
|
0.76
|
0.43
|
0
|
1
|
Credit service (= 1 if they used)
|
0.31
|
0.46
|
0
|
1
|
Age of the household head (years)
|
50
|
13.41
|
22
|
99
|
Use of improved seed (= 1if they applied)
|
0.2
|
0.4
|
0
|
1
|
Planting method (=1 if they applied row planting)
|
0.12
|
0.33
|
0
|
1
|
Livestock holding (TLU)
|
4.27
|
4.31
|
0
|
30
|
Household size (number)
|
8
|
2.98
|
1
|
16
|
Application of mineral fertilizer (= 1 if they applied)
|
0.75
|
0.43
|
0
|
1
|
Distance to the nearest market (km)
|
67.8
|
42.09
|
2.9
|
201.6
|
Soil fertility of the plot (= I if the plot is fertile )
|
0.38
|
0.48
|
0
|
1
|
- Average neighbor farmers’ characteristics
|
|
|
|
|
Neighbor farmers’ use of improved seed (= 1if they applied)
|
0.31
|
0.28
|
0
|
1
|
Neighbor farmers’ level of community participation (= 1if they participated)
|
0.74
|
0.27
|
0
|
1
|
Neighbor farmers’ use of mineral fertilizer (= 1if they applied)
|
0.73
|
0.32
|
0
|
1
|
Neighbor farmers’ extension service provision (= 1if they participated)
|
0.54
|
0.35
|
0
|
1
|
Neighbor farmers’ level of education (years of schooling)
|
2.16
|
1.83
|
0
|
10
|
Neighbor farmers’ Teff planting method (= 1if they applied row planting)
|
0.12
|
0.18
|
0
|
1
|
*SD indicates Standard Deviation, pooled data (N = 1716)
Source: Own analysis based on ESS (2014 and 2016)
Table 2: Time-varying model of stochastic frontier based on Battese and Coelli (1992)
Input variables
|
Estimated value
|
Robust Std. Err.
|
Z
|
P > |z|
|
lnLand
|
.1206475
|
.0352202
|
3.43
|
0.001***
|
lnLabor
|
.2853783
|
.0617842
|
4.62
|
0.000***
|
lnFertilizer
|
.0076977
|
.0037747
|
2.04
|
0.04**
|
lnSeed
|
.4310508
|
.0970771
|
4.44
|
0.000***
|
lnOxen
|
.0197815
|
.0617685
|
0.32
|
0.749
|
lnLand*lnLabor
|
-.0378225
|
.0169698
|
-2.23
|
0.026 **
|
lnLand*lnFertilizer
|
.0005562
|
.0011528
|
0.48
|
0.629
|
lnLand*lnSeed
|
-.0081779
|
.0253831
|
-0.32
|
0.747
|
lnLand*lnOxen
|
.0014157
|
.0144446
|
0.10
|
0.922
|
lnLabor*lnFertilizer
|
.0012113
|
.0020587
|
0.59
|
0.558
|
lnLabor*lnSeed
|
-.0183248
|
.0339553
|
-0.54
|
0.589
|
lnLabor*lnOxen
|
-.0209723
|
.0229249
|
-0.91
|
0.360
|
lnFertilizer*lnSeed
|
-.0043527
|
.0027864
|
-1.56
|
0.118
|
lnFertilizer*lnOxen
|
-.0021991
|
.0014632
|
-1.50
|
0.133
|
lnSeed*lnOxen
|
.0259242
|
.0351486
|
0.74
|
0.461
|
time (t)
|
.000335
|
.0000676
|
4.96
|
0.000 ***
|
t*lnLand
|
-.000017
|
.0000152
|
-1.12
|
0.264
|
t*lnLabor
|
-.0003638
|
.0000406
|
-8.96
|
0.000 ***
|
t*lnFertilizer
|
-4.93e-06
|
1.52e-06
|
-3.23
|
0.001 ***
|
t*lnSeed
|
.0003362
|
.0000497
|
6.76
|
0.000 ***
|
t*lnOxen
|
2.52e-06
|
.0000241
|
0.10
|
0.917
|
β0(Constant)
|
-2.265807
|
.3205598
|
-7.07
|
0.000 ***
|
/Lnsigma2
|
-5.30692
|
.0672164
|
-78.95
|
0.000 ***
|
/ilgtgamma (γ)
|
-1.287981
|
.3307949
|
-3.89
|
0.000 ***
|
µ
|
.2426185
|
.1206865
|
2.01
|
0.044 *
|
Ƞ (eta)
|
.3099621
|
.132728
|
2.34
|
0.020*
|
sigma2
|
.0049572
|
.0003332
|
Gamma
|
.2161947
|
.0560547
|
sigma_µ2
|
.0010717
|
.000325
|
Sigma_v2
|
.0038855
|
.0002473
|
Wald chi2(19)
|
14001.90
|
0.0000***
|
Log pseudo-likelihood
|
2078.0198
|
*** => significant at 1% level; ** => significant at 5% level; and * => significant at 10% level; N = 1716; number of panel groups = 858; t = 2 years. The dependent variable is a logarithm of Teff yield (lnYield). Source: Own analysis based on ESS (2014 and 2016) data
Table 3: Technical efficiency scores and Teff yield gap analysis due to technical inefficiency
Variable
|
Mean
|
SD*
|
Min
|
Max
|
Actual Yield (ton ha-1)
|
1.213
|
0.266
|
0.641
|
2.05
|
Technical Efficiency
|
0.785
|
0.017
|
0.679
|
0.925
|
Potential yield (ton ha-1)
|
1.516
|
0.325
|
0.799
|
2.545
|
Yield gap (ton ha-1)
|
0.303
|
0.064
|
0.107
|
0.495
|
* = Standard Deviation, N = 1716, number of panel groups = 858, and t = 2 years
Source: Own analysis based on ESS (2014 and 2016) data
Table 4: The results of the CRE estimation of the SLX model
Parameters
|
Without neighborhood effects
estimate (robust std. error)
|
With neighborhood effects
estimate (robust std. error)
|
|
Estimated value
|
SE+
|
Estimated value
|
SE+
|
Farmers own farm characteristics
|
Constant
|
0.5528113 ***
|
0.0171147
|
0.4341563***
|
(0.0125214
|
Gender ( = 1 if the household head is male)
|
-0.0105174 ***
|
0.0027761
|
-0.0051681***
|
0.0018365
|
Education (years of schooling)
|
-0.0026602***
|
0.0004304
|
-0.0017335***
|
0.0003007
|
Age (years)
|
-0.0059423***
|
0.0006466
|
-0.0030702***
|
0.0004516
|
Age^2
|
0.0000341 ***
|
5.94e-06
|
0.0000187***
|
4.17e-06
|
Family size (number)
|
-0.0040373***
|
0.0007878
|
-0.002803 ***
|
0.0004972
|
Livestock holding (TLU)
|
-0.0007244
|
0.0007324
|
-0.0004491
|
0.0004836
|
Extension (= 1 if they participated)
|
-0.0098264*
|
0.0051281
|
-0.0032904
|
0.0033652
|
Credit (= 1 if they used)
|
0.0032793
|
0.0045804
|
0.00066
|
0.0031472
|
Community participation (= 1 if they participated)
|
-0.0274244***
|
0.0055334
|
-0.0093939**
|
0.0037042
|
Improved seed (= 1if they applied)
|
-0.015873***
|
0.0045018
|
-0.0011051
|
0.0029046
|
Fertilizer usage (= 1 if they applied)
|
0.0006612
|
0.0067365
|
-0.0071943
|
0.0044972
|
Soil fertility ( = 1 if the plot is fertile)
|
-0.0188108***
|
0.0039822
|
-0.0056838 **
|
0.0027743
|
Planting method (=1 if they applied row planting)
|
-0.0402027***
|
0.00468
|
-0.0084955**
|
0.0034658
|
Distance to market (km)
|
-0.0000763
|
0.0000804
|
-0.0000805
|
0.000051
|
Distance to market^2
|
1.76e-08
|
4.31e-07
|
1.92e-07
|
2.65e-07
|
Average Neighbors’ farm characteristics
|
Z_Ext (neighbors’ extension service participation )
|
-
|
-
|
-0.0067002
|
0.0080697
|
Z_FertilUsage (neighbors’ fertilizer usage)
|
-
|
-
|
-0.0220136*
|
0.0122593
|
Z_ comParticipation (neighbors’ community participation )
|
-
|
-
|
-0.0483096***
|
0.0083671
|
Z_Improvseed (neighbors’ improved seed usage)
|
-
|
-
|
-0.1205222***
|
0.0045714
|
Z_Education (neighbors’ education)
|
-
|
-
|
0.0004379
|
0.0004519
|
Z_Planting (neighbors’ row planting usage)
|
-
|
-
|
-0.0448689***
|
0.0083998
|
Sigma_u
|
0.01395214
|
|
0.01382005
|
|
Sigma_e
|
0.0065134
|
|
0.00651933
|
|
Rho
|
0.82105975
|
|
0.81797673
|
|
Wald chi2
|
2136.00***
|
|
4172.46***
|
|
R2-within =
|
0.2904
|
|
0.7023
|
|
R2-between =
|
0.3439
|
|
0.5176
|
|
R2-overall =
|
0.2226
|
|
0.6457
|
|
*** => statistically significant at the 99% confidence level; ** => statistically significant at the 95% confidence level; * => statistically significant at the 90% confidence level; + => robust Standard Error; the dependent variable is technical inefficiency score; N = 858; and t = 2 years; neighborhood effect variables are denoted with a leading “Z_”
Source: Own analysis based on ESS (2014 and 2016) data
Table 5: Correlation matrix between Xit and Zit variables
Variables
|
Average neighbor farmers’ socioeconomics characteristics (neighborhood effects )
|
farmers’ own socioeconomics characteristics
|
improved seed
|
Community participation
|
fertilizer
|
extension
|
education
|
planting method
|
Gender
|
-0.0076
|
0.0427
|
0.0042
|
-0.0066
|
-0.0012
|
-0.0122
|
Education
|
0.0273
|
0.0377
|
0.0196
|
-0.0794
|
0.2945
|
0.0498
|
Age
|
0.0798
|
-0.0059
|
0.0741
|
0.0323
|
0.0309
|
0.0783
|
Credit
|
-0.0264
|
0.0320
|
0.2347
|
0.1865
|
-0.0090
|
-0.0172
|
Community participation
|
0.1087
|
0.2354
|
-0.0044
|
0.0579
|
0.0627
|
0.0632
|
Improved seed usage
|
0.1697
|
0.0585
|
-0.0361
|
0.0237
|
0.0498
|
0.1616
|
Planting method usage
|
0.2073
|
0.0392
|
-0.0102
|
0.0144
|
0.0410
|
0.2272
|
TLU
|
-0.0145
|
-0.1136
|
-0.0720
|
-0.0749
|
-0.0091
|
-0.0198
|
Household size
|
0.0893
|
0.0562
|
-0.0289
|
-0.0190
|
0.1188
|
0.1039
|
Fertilizer application
|
-0.0253
|
-0.0215
|
0.4397
|
0.3123
|
0.0234
|
0.0005
|
Distance market
|
-0.0610
|
0.0079
|
-0.2477
|
-0.2808
|
0.1251
|
-0.0409
|
Soil fertility of the plot
|
0.1221
|
0.0347
|
-0.0307
|
-0.0035
|
-0.0208
|
0.1262
|
Source: Own analysis based on ESS (2014 and 2016) data
Table 6: VIF test
Variable
|
VIF
|
1/VIF
|
Age
|
42.51
|
0.023525
|
Age^2
|
42.45
|
0.023556
|
Dismkt
|
10.83
|
0.092337
|
Dismkt^2
|
10.54
|
0.094855
|
Z_Ext
|
2.12
|
0.471089
|
Z_FertilUsage
|
2.08
|
0.479717
|
Ext
|
1.61
|
0.619550
|
FertilUsage
|
1.60
|
0.625637
|
Z _Improvseed
|
1.51
|
0.663607
|
Z _Planting
|
1.40
|
0.715134
|
Z _Education
|
1.31
|
0.765789
|
Z _comParticipation
|
1.29
|
0.773285
|
Planting
|
1.26
|
0.790800
|
Education
|
1.26
|
0.791895
|
Family size
|
1.25
|
0.799077
|
Improvseed
|
1.24
|
0.809642
|
ComParticipation
|
1.23
|
0.812060
|
Credit
|
1.10
|
0.905402
|
SoilFertility
|
1.07
|
0.935783
|
TLU
|
1.07
|
0.936682
|
Gender
|
1.05
|
0.954114
|
Mean VIF
|
6.18
|
Source: Own analysis based on ESS (2014 and 2016) data
Table 7: Hausman test
|
Coefficients
|
|
(b)
FE
|
(B)
RE
|
(b-B)
Differences
|
Sqrt (diag(v_b – v_B))
S.E.
|
Age
|
-.0439849
|
-.0030344
|
-.0409505
|
.0024591
|
Age^2
|
-1.89e-06
|
.0000186
|
-.0000204
|
.0000224
|
HHSIZE
|
-.0002243
|
-.0030917
|
.0028675
|
.0002794
|
TLU
|
-.0001077
|
.0000597
|
-.0001674
|
.0001735
|
Ext
|
-.0021317
|
-.0046552
|
.0025235
|
.0009718
|
Credit
|
-.0003685
|
.0002427
|
-.0006112
|
.0008419
|
SWC
|
-.0030219
|
-.0114155
|
.0083936
|
.0010455
|
Improvseed
|
.0047258
|
-.0014693
|
.0061951
|
.0008747
|
FertilUsage
|
.0006042
|
-.0052613
|
.0058655
|
.0014233
|
Soilfertility
|
.0004982
|
-.0067517
|
.0072499
|
.0006704
|
SowingMethod
|
.0058268
|
-.0113201
|
.0171469
|
.0010461
|
Z _Ext
|
-.00032
|
.0007485
|
-.0010685
|
.0028309
|
Z _FertilUsage
|
-.0019523
|
-.0043786
|
.0024262
|
.0044736
|
Z _ comParticipation
|
-.001068
|
-.0300698
|
.0290018
|
.0026985
|
Z _Improvseed
|
.0004267
|
-.1170868
|
.1175136
|
.0034047
|
Z _Planting
|
-.0017314
|
-.0408359
|
.0391045
|
.0023141
|
b = consistent under Ho and Ha; obtained from xtreg
|
B = inconsistent under Ha, efficient under Ho; obtained from xtreg
|
Test: Ho: difference in coefficients not systematic
|
chi2(16) = (b-B)'[(V_b-V_B)^(-1)](b-B) = 1591.51
|
Prob>chi2 = 0.0000
|
Source: Own analysis based on ESS (2014 and 2016) data