International trade and agricultural production: Evidence from the Southern African Development Community sub-region

Figures & data

Table 1: Changes in agricultural exports to machinery and chemical imports from the SACU, SADC, SSA and rest of the world for some SADC countries (2001 to 2006)

	Agricultural exports				Machinery imports				Chemical imports
Country	World	SSA	SADC	SACU	World	SSA	SADC	SACU	World	SSA	SADC	SACU
Botswana	−15.82	0.09	13.40	2.33	−6.70	0.08	−0.15	6.76	−3.39	−0.03	−0.90	4.33
Namibia	−9.62	3.90	3.11	2.61	2.03	0.00	0.07	−2.09	9.49	0.14	−0.07	−9.57
Swaziland	−2.88	3.51	−0.80	0.16	15.88	0.07	2.51	−18.46	25.11	0.00	8.24	−33.35
South Africa	−2.87	−0.10	3.73	−0.75	0.22	−0.02	−0.18	0.00	0.03	0.03	−0.07	0.01
Tanzania	−5.16	3.01	1.07	1.07	−5.20	0.20	−0.15	5.15	6.09	−7.16	−0.17	1.23
Malawi	−10.82	−2.29	6.66	6.45	−8.16	−0.54	−0.90	9.60	22.54	1.13	−4.64	−19.04
Zambia	−3.42	−10.13	17.16	−3.61	12.95	−0.09	0.69	−13.55	10.20	1.12	−8.31	−3.02
Zimbabwe	−9.05	−1.60	3.20	7.46	−6.98	−0.26	0.19	7.06	−9.45	−0.14	0.83	8.75
Madagascar	0.19	0.03	−0.11	−0.11	−3.24	0.04	−0.59	3.78	1.03	0.55	−0.85	−0.72
Mozambique	−12.14	−0.39	12.46	0.06	−5.71	−0.26	1.05	4.92	−7.05	0.27	−0.19	6.96
Mauritius	3.25	−3.53	0.02	0.27	2.45	0.02	−0.01	−2.47	3.71	−0.14	0.16	−3.72

Source: Author's computation using the COMTRADE database (www.comtrade.un.org).

Table 2: Summary statistics

Variable	Observations	Mean	Standard deviation	Minimum	Maximum
Agricultural VA (constant 2 000 US$)	394	1.19×10^9	1.15×10^9	1.14×10^8	5.02×10^9
Tariffs
SACU	394	4.48×10^0	4.40×10^0	1.00×10^–2	2.93×10^1
SADC net SACU	394	1.83×10^1	1.25×10^1	1.00×10^–2	6.09×10^1
SSA net SADC	394	3.36×10^1	1.99×10^1	4.00×10^–2	8.67×10^1
World net SSA	394	1.07×10^1	1.53×10^1	1.00×10^–2	1.21×10^2
Agricultural exports
Total	394	6.58×10^5	1.21×10^6	1.39×10^2	6.99×10^6
SACU	394	1.30×10^5	3.44×10^5	1.91×10^–1	1.44×10^6
SADC net SACU	394	2.24×10^4	6.57×10^4	1.60×10^–2	5.55×10^5
SSA net SADC	394	1.16×10^4	2.52×10^4	2.50×10^0	2.20×10^5
World net SSA	394	494 167.9	837 837.6	11.655	5 119 845
Machinery imports
Total	394	1.14×10^6	3.10×10^6	1.00×10^4	2.94×10^7
SACU	394	7.88×10^4	1.57×10^5	1.66×10^0	1.06×10^6
SADC net SACU	394	4.43×10^3	9.37×10^3	4.81×10^–1	8.37×10^4
SSA net SADC	394	2.03×10^3	4.61×10^3	5.70×10^–1	4.24×10^4
World net SSA	394	1.06×10^6	3.11×10^6	5.72×10^3	2.93×10^7
Chemicals imports
Total	394	3.48×10^5	8.52×10^5	7.15×10^3	7.37×10^6
SACU	394	4.40×10^4	6.40×10^4	5.25×10–^1	3.25×10^5
SADC net SACU	394	3.00×10^3	5.27×10^3	5.46×10–^1	4.42×10^4
SSA net SADC	394	2.34×10^3	4.30×10^3	−2.07×10^3	3.03×10^4
World net SSA	394	2.99×10^5	8.59×10^5	4.54×10^2	7.37×10^6
Other variables
Land (ha)	394	4.49×106	3.84×10^6	9.90×10^4	1.49×10^7
Labour (1000 persons)	394	4.48×103	3.86×10^3	5.20×10^1	1.60×10^4
Livestock production index	394	8.50×101	1.92×10^1	3.00×10^1	1.36×102
Share of irrigated land	394	7.61×100	9.32×10^0	1.41×10^–1	3.06×10^1
Primary enrolment rate	394	9.11×101	1.98×10^1	4.81×10^1	1.39×10^2
Secondary enrolment rate	394	3.18×101	2.48×10^1	5.18×10^0	9.47×10^1
Tertiary enrolment rate	394	3.63×100	3.95×10^0	2.91×10^–1	1.72×10^1
Life expectancy (years)	394	5.01×101	8.17×10^0	3.91×10^1	7.33×10^1

Table 3: Fixed-effect estimation results (Breusch-Pagan Statistics are for random effects)^a

	Model 1			Model 2			Model3
	Coefficient	SE	p	Coefficient	SE	p	Coefficient	SE	p
Constant	9.226***	1.801	0.000	12.183***	1.777	0.000	8.747***	1.695	0.000
ln N	0.479***	0.143	0.001	0.132	0.143	0.357	0.547***	0.133	0.000
ln L	0.464***	0.049	0.000	0.604***	0.060	0.000	0.383***	0.054	0.000
ln LS	0.160**	0.058	0.006	0.129*	0.066	0.051	0.200***	0.056	0.000
ln IR	0.158**	0.072	0.030	0.232***	0.075	0.002	0.166**	0.072	0.022
ln PE(t-5)	0.200	0.092	0.230	0.100	0.093	0.285	0.013	0.078	0.867
ln SE(t-5)	0.178**	0.015	0.000	0.189***	0.028	0.000	0.135***	0.033	0.000
ln TE(t-5)	-0.083***	0.021	0.002	-0.099***	0.030	0.001	-0.038	0.029	0.193
ln LE	0.315***	0.093	0.001	0.090	0.098	0.356	0.327***	0.102	0.001
ln X	0.016	0.010	0.123	–	–	–	–	–	–
ln MA	0.102***	0.025	0.000	–	–	–	0.093***	0.024	0.000
ln C	0.069***	0.023	0.003	–	–	–	0.065***	0.023	0.004
ln Xsacu	–	–	–	0.017*	0.009	0.063	–	–	–
ln Xsadc	–	–	–	0.021***	0.005	0.000	–	–	–
ln Xssa	–	–	–	0.003	0.005	0.581	–	–	–
ln Xw	–	–	–	0.016	0.019	0.409	–	–	–
ln MAsacu	–	–	–	0.022**	0.010	0.031	–	–	–
ln MAsadc	–	–	–	0.012	0.008	0.110	–	–	–
ln MAssa	–	–	–	0.008	0.007	0.264	–	–	–
ln MAw	–	–	–	0.029	0.029	0.326	–	–	–
ln Csacu	–	–	–	0.021**	0.011	0.044	–	–
ln Csadc	–	–	–	0.008	0.008	0.341	–	–
ln Cssa	–	–	–	0.001	0.009	0.951	–	–
ln Cw	–	–	–	0.040**	0.018	0.036	–	–
ln TAsacu	–	–	–	–	–		−0.008**	0.003	0.015
ln TAsadc	–	–	–	–	–		−0.005	0.007	0.453
ln TAssa	–	–	–	–	–		−0.044	0.028	0.122
ln TAw	–	–	–	–	–		−0.067	0.050	0.178
Observations	360	359	374
R^2 within	0.73	0.76	0.72
R^2 between	0.65	0.62	0.63
R^2 overall	0.59	0.58	0.57
F(14, 366)	86.10(0.000)	53.02(0.000)	67.83(0.000)
Fui(13, 366)	203.20(0.000)	82.68(0.000)	225.24(0.000)
Hausmanχ^2	19.29(0.771)	8682.46(0.000)	1091.29(0.000)
Breuch — Pagan^b	903.93 (0.000)	142.32 (0.000)	759.77 (0.000)

Note: Dependent variable: log of Agric. output (at constant 2000 US$). Variables are evaluated are three significance levels: ***1%, **5% and *10% level of significance. ^aIn each model, the elasticities are given in the first column of figures, followed by the standard errors (SEs) and the probability values (p). ^bTests for random-effect model.

Table A1: Variables, definitions and measurements

Variable	Definition	Measurement	Data source
y	Agricultural value added	At constant 2000 US$	WDI 2008
N	Arable land	Ha	WDI 2008
L	Labour force in agriculture	Persons	FAO database
LS	Livestock	Index	WDI 2008
IR	Share of irrigated land	Ratio	FAO
PE	Primary enrolment rate (five-year lagged)	Rate	WDI 2008
SE	Secondary enrolment rate (five-year lagged)	Rate	WDI 2008
TE	Tertiary enrolment rate (five-year lagged)	Rate	WDI 2008)
LE	Life expectancy	Years	WDI 2008
X	Export	US$1 000	UN COMTRADE
MA	Machinery	US$1 000	UN COMTRADE
Xsacu	SADC export to SACU	US$1 000	UN COMTRADE
Xsadc	SADC export to SADC	US$1 000	UN COMTRADE
Xssa	SADC export to SSA	US$1 000	UN COMTRADE
Xw	SADC export to rest of the World	US$1 000	UN COMTRADE
MAsacu	Machinery import by SADC from SACU	US$1 000	UN COMTRADE
MAsadc	Machinery import by SADC from SADC	US$1 000	UN COMTRADE
MAssa	Machinery import by SADC from SSA	US$1 000	UN COMTRADE
MAw	Machinery import by SADC from rest of the World	US$1 000	UN COMTRADE
Csacu	Chemical import by SADC from SACU	US$1 000	UN COMTRADE
Csadc	Chemical import by SADC from SADC	US$1 000	UN COMTRADE
Cssa	Chemical import by SADC from SSA	US$1 000	UN COMTRADE
Cw	Chemical import by SADC from rest of the world	US$1 000	UN COMTRADE
TAsacu	Tariffs imposed by SACU member states to those of SADC	Trade weighted values	UNCTAD TRAINS
TAsadc	Intra-SADC tariffs	Trade weighted values	UNCTAD TRAINS
TAssa	Tariffs imposed by SSA country member states to those of SADC	Trade weighted values	UNCTAD TRAINS
TAw	Tariffs imposed by rest of the world to SADC member states	Trade weighted values	UNCTAD TRAINS

Table A2: Pair-wise correlation coefficients

Variable	Coefficient	Significance	Variable	Coefficient	Significance
	0.802	0.000		0.536	0.000
	0.648	0.000		−0.396	0.000
	0.176	0.001		0.296	0.000
	0.177	0.000		0.577	0.000
(t-5)	0.249	0.099		0.665	0.000
(t-5)	0.216	0.000		−0.528	0.000
(t-5)	−0.002	0.962		0.276	0.000
	0.030	0.047		0.595	0.000
	0.514	0.000		0.691	0.000
	0.520	0.000		−0.033	0.010
	0.514	0.000		−0.030	0.054
	0.373	0.000		−0.069	0.173
	0.273	0.000		−0.272	0.000
	0.441	0.000

Table A3: GLS estimation results (last two columns contain fixed-effect estimates without human capital)

	Model 1		Model 2		Model3		No human capital
	Coefficient	SE	Coefficient	SE	Coefficient	SE	Coefficient	SE
Constant	8.131***	1.085	11.133***	0.928	8.451***	1.131	7.876***	1.904
	0.159***	0.058	0.133***	0.046	0.102*	0.059	0.534***	0.153
	0.257***	0.056	0.222***	0.036	0.378***	0.055	0.369***	0.053
	0.364***	0.116	0.361***	0.084	0.435***	0.120	0.351***	0.054
	0.128***	0.024	0.143**	0.021	0.116*	0.020	0.275***	0.074
	0.118	0.160	0.100	0.122	0.105**	0.163	–	–
	0.523***	0.074	0.413***	0.058	0.496***	0.071	–	–
	−0.249	0.049	−0.124***	0.042	−0.196***	0.048	–	–
	1.625***	0.183	0.702***	0.164	2.073***	0.190	–	–
	0.211***	0.026	–	–	–	–	0.019*	0.012
	0.091**	0.044	–	–	0.085**	0.042	0.103***	0.027
	0.324***	0.059	–	–	0.380***	0.063	0.080***	0.026
	–	–	0.012	0.010	–	–	–	–
	–	–	0.030***	0.008	–	–	–	–
	–	–	0.014	0.010	–	–	–	–
	–	–	0.141***	0.019	–	–	–	–
	–	–	0.043***	0.011	–	–	–	–
	–	–	0.081***	0.013	–	–	–	–
	–	–	0.130	0.013	–	–	–	–
	–	–	0.064*	0.045	–	–	–	–
	–	–	0.033**	0.013	–	–	–	–
	–	–	0.042***	0.014	–	–	–	–
	–	–	0.041***	0.013	–	–	–	–
	–	–	0.025**	0.041	–	–	–	–
	–	–	–	–	−0.018**	0.007	–	–
	–	–	–	–	−0.026**	0.013	–	–
	–	–	–	–	−0.014	0.032	–	–
	–	–	–	–	−0.104***	0.015	–	–
Observations	380	379	380	380
	903.93 (0.000)	142.32 (0.000)	759.77 (0.000)

Note: Dependent variable: log of Agric. output (at constant 2000 US$). Variables are evaluated are three significance levels: ***1%, ** 5% and *10% level of significance