Introduction
Theory
Migration Systems Theory (MST)
Migratory dynamics in the North and South
North–North flows
South–South flows
South–North flows
Materials and methods
Methods: the Stochastic Actor-oriented Model (SAOM)
Data and measures
Dependent variable(s)
-
North–North migration networkt = 1 for all flows which size is in the upper quartile of the distribution of flows between countries in the Global North at time t; 0 otherwise.
-
South–South migration networkt = 1 for all flows which size is in the upper quartile of the distribution of flows between countries in the Global South at time t; 0 otherwise.
-
North–South migration networkt = 1 for all flows which size is in the upper quartile of the distribution of flows from countries in the Global North to countries in the Global South (and vice versa) at time t; 0 otherwise.
Covariates
Network effect | Equation | Visual representation |
---|---|---|
Outdegree | \(\sum\limits_{j} {x_{ij} }\) | |
Dyadic reciprocity | \(\sum\limits_{j} {x_{ij} x_{ji} }\) | |
Indegree popularity (sqrt) | \(\sum\limits_{j} {x_{ij} \sqrt {x_{ + j} } }\) | |
Outdegree popularity (sqrt) | \(\sum\limits_{j} {x_{ij} \sqrt {x_{j + } } }\) | |
Outdegree activity (sqrt) | \(\left( {x_{i + } } \right)^{1.5}\) | |
Transitive triads | \(\sum\limits_{j,h} {x_{ih} x_{ij} x_{jh} }\) | |
Cyclic triads | \(\sum\limits_{j,h} {x_{ij} x_{jh} x_{hi} }\) | |
Transitive reciprocated triads | \(\sum\limits_{j,h} {x_{hi} x_{ih} x_{ij} x_{jh} }\) | |
GWDSP—mixed-stars | \(\sum\limits_{h = 1;h \ne i}^{n} {e^{\alpha } \left\{ {1 - \left( {1 - e^{ - \alpha } } \right)\sum\limits_{j = 1}^{n} {x_{ij} x_{jh} } } \right\}}\) | |
GWDSP—in-stars | \(\sum\limits_{h = 1;h \ne i}^{n} {e^{\alpha } \left\{ {1 - \left( {1 - e^{ - \alpha } } \right)\sum\limits_{j = 1}^{n} {x_{ij} x_{hj} } } \right\}}\) |
Results
Descriptive results
1990–1995 | 1995–2000 | 2000–2005 | 2005–2010 | 2010–2015 | |
---|---|---|---|---|---|
North–North flows | |||||
Density | 0.248 | 0.248 | 0.248 | 0.249 | 0.249 |
Centralization (indegree) | 0.640 | 0.619 | 0.597 | 0.533 | 0.533 |
Mean in-degree (std. dev) | 11.92 (10.22) | 11.99 (9.81) | 11.92 (9.99) | 11.94 (8.95) | 11.96 (9.22) |
Mean out-degree (std. dev) | 11.92 (7.83) | 11.90 (8.84) | 11.92 (9.28) | 11.94 (9.74) | 11.96 (9.38) |
Number of nodes | 49 | 49 | 49 | 49 | 49 |
Number of isolates | 0 | 1 | 2 | 1 | 0 |
Dyad census | |||||
Number of mutual dyads | 219 | 223 | 233 | 233 | 246 |
Number of asymmetric dyads | 146 | 137 | 118 | 119 | 94 |
Number of null dyads | 811 | 816 | 825 | 824 | 836 |
Relevant triads | |||||
Number of transitive triads (030T) | 39 | 42 | 28 | 36 | 22 |
Number of 021U triads | 283 | 209 | 213 | 89 | 95 |
Number of cyclic triangles (030C) | 0 | 0 | 1 | 0 | 0 |
Number of 021C triads | 150 | 181 | 120 | 136 | 74 |
Number of trans. rec. triads (120C) | 37 | 39 | 42 | 38 | 34 |
South–South flows | |||||
Density | 0.265 | 0.264 | 0.258 | 0.268 | 0.254 |
Centralization (indegree) | 0.627 | 0.486 | 0.634 | 0.647 | 0.594 |
Mean in-degree (std. dev) | 35.57 (22.02) | 35.34 (22.46) | 34.63 (21.69) | 35.98 (22.16) | 34 (21.98) |
Mean out-degree (std. dev) | 35.57 (22.23) | 35.34 (21.48) | 34.63 (20.37) | 35.98 (21.85) | 34 (20.82) |
Number of nodes | 135 | 135 | 135 | 135 | 135 |
Number of isolates | 0 | 0 | 0 | 0 | 0 |
Dyad census | |||||
Number of mutual dyads | 1760 | 1794 | 1819 | 1872 | 1952 |
Number of asymmetric dyads | 1282 | 1183 | 1037 | 1113 | 686 |
Number of null dyads | 6003 | 6068 | 6189 | 6060 | 6407 |
Relevant triads | |||||
Number of transitive triads (030T) | 2049 | 1345 | 1232 | 1490 | 322 |
Number of 021U triads | 5863 | 6758 | 5890 | 5209 | 3738 |
Number of cyclic triangles (030C) | 21 | 5 | 8 | 7 | 0 |
Number of 021C triads | 2937 | 2250 | 2072 | 1739 | 412 |
Number of trans. rec. triads (120C) | 1114 | 946 | 949 | 927 | 439 |
North–South flows | |||||
Density | 0.098 | 0.098 | 0.098 | 0.097 | 0.097 |
Centralization (indegree) | 0.517 | 0.561 | 0.528 | 0.539 | 0.523 |
Mean in-degree (std. dev) | 17.86 (21.23) | 17.87 (23.32) | 17.85 (23.25) | 17.83 (22.32) | 17.83 (22.51) |
Mean out-degree (std. dev) | 17.86 (18.42) | 17.87 (17.15) | 17.85 (17.50) | 17.83 (18.37) | 17.83 (18.21) |
Number of nodes | 184 | 184 | 184 | 184 | 184 |
Number of isolates | 1 | 1 | 2 | 0 | 1 |
Dyad census | |||||
Number of mutual dyads | 1200 | 1202 | 1222 | 1260 | 1322 |
Number of asymmetric dyads | 887 | 884 | 840 | 760 | 637 |
Number of null dyads | 14,749 | 14,750 | 14,774 | 14,816 | 14,877 |
Relevant triads | |||||
Number of transitive triads (030T) | – | – | – | – | – |
Number of 021U triads | 6958 | 10,661 | 9330 | 6595 | 5714 |
Number of cyclic triangles (030C) | – | – | – | – | – |
Number of 021C triads | 4129 | 2439 | 1818 | 1782 | 980 |
Number of trans. rec. triads (120C) | – | – | – | – | – |
Inferential results
North–North networks | South–South networks | North–South networks | |
---|---|---|---|
Estimate (S.E.) | Estimate (S.E.) | Estimate (S.E.) | |
Rate parameters | |||
Period 1 | 4.116 (0.436) | 18.569 (0.700) | 10.324 (0.442) |
Period 2 | 5.533 (0.562) | 18.120 (0.701) | 9.324 (0.418) |
Period 3 | 4.088 (0.439) | 10.557 (0.405) | 5.011 (0.249) |
Period 4 | 4.383 (0.468) | 12.605 (0.484) | 5.272 (0.256) |
Network endogenous effects | |||
Outdegree | − 4.280*** (0.377) | − 2.557*** (0.156) | − 4.815*** (0.106) |
Reciprocity | 2.787*** (0.235) | 3.101*** (0.106) | 1.955*** (0.055) |
Transitive triads (030T) | 0.120*** (0.021) | 0.053*** (0.003) | – |
Transitive recipr. triads (120C) | − 0.108*** (0.032) | − 0.037*** (0.005) | – |
Cyclic triads (030C) | 0.004 (0.042) | 0.026*** (0.007) | – |
GWDSP mixed-star | – | – | − 0.078*** (0.010) |
GWDSP in-star | – | – | 0.053*** (0.008) |
Indegree—popularity (sqrt) | 0.852*** (0.141) | 0.600*** (0.032) | 0.520*** (0.028) |
Outdegree—popularity (sqrt) | − 0.717*** (0.180) | − 0.883*** (0.050) | − 0.154*** (0.032) |
Outdegree—activity (sqrt) | 0.236*** (0.051) | 0.099*** (0.015) | 0.222*** (0.012) |
MST linkages | |||
Common language | 0.785*** (0.208) | 0.335*** (0.035) | 0.607*** (0.058) |
Contiguous border | 0.960*** (0.169) | 1.688*** (0.204) | 1.235*** (0.292) |
Same region | 0.107 (0.111) | 0.603*** (0.045) | 1.052*** (0.103) |
Shared IGO | 0.137 (0.124) | 0.371*** (0.051) | 0.288*** (0.095) |
GDP—inflows | − 0.028 (0.044) | 0.142*** (0.018) | − 0.004 (0.020) |
GDP—outflows | 0.029 (0.041) | − 0.170*** (0.021) | − 0.027 (0.019) |
Other controls | |||
Old age dependency—inflows | 0.009 (0.010) | 0.002 (0.006) | 0.003 (0.004) |
Old age dependency—outflows | − 0.026*** (0.009) | − 0.015** (0.006) | − 0.015*** (0.004) |
Population—inflows | 0.181** (0.077) | 0.055*** (0.015) | 0.092*** (0.019) |
Population—outflows | 0.122 (0.063) | 0.037** (0.015) | 0.162*** (0.018) |
Coups—inflows | 0.632 (− 2.634) | − 0.636*** (0.148) | 0.233 (0.298) |
Coups—outflows | − 1.651 (2.524) | 0.146 (0.142) | − 0.017 (0.205) |
Goodness of fit | |||
Indegree or inflows | 0.896 | 0 | 0.044 |
Outdegree or outflows | 0.067 | 0.026 | 0 |
Transition period 1: 1990–1995 to 1995–2000 | Transition period 2: 1995–2000 to 2000–2005 | Transition period 3: 2000–2005 to 2005–2010 | Transition period 4: 2005–2010 to 2010–2015 | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
North–North network | South–South network | North–South network | North–North network | South–South network | North–South network | North–North network | South–South network | North–South network | North–North network | South–South network | North–South network | |
Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | Estimate (S.E) | |
Rate parameter | 4.003 (0.421) | 18.185 (0.756) | 9.308 (0.400) | 5.250 (0.521) | 17.500 (0.736) | 9.465 (0.436) | 3.859 (0.423) | 10.657 (0.439) | 5.084 (0.267) | 4.272 (0.475) | 12.350 (0.488) | 5.202 (0.266) |
Network endogenous effects | ||||||||||||
Outdegree | − 5.951*** (0.986) | − 1.561*** (0.292) | − 4.822*** (0.209) | − 4.979*** (0.710) | − 1.926*** (0.319) | − 4.739*** (0.194) | − 2.672*** (0.825) | − 2.392*** (0.388) | − 5.616*** (0.346) | − 4.245*** (0.874) | − 4.744*** (0.462) | − 4.99*** (0.260) |
Reciprocity | 2.264*** (0.496) | 2.837*** (0.179) | 1.813*** (0.114) | 2.699*** (0.483) | 2.839*** (0.211) | 1.824*** (0.100) | 3.047*** (0.535) | 2.838*** (0.173) | 1.990*** (0.123) | 3.587*** (0.543) | 4.235*** (0.292) | 2.593*** (0.141) |
Transitive triads (030T) | 0.133*** (0.041) | 0.067*** (0.004) | – | 0.093* (0.041) | 0.048*** (0.005) | – | 0.172*** (0.048) | 0.072*** (0.007) | – | 0.104 (0.053) | 0.019* (0.008) | – |
Tran. recipr. tri. (120C) | − 0.086 (0.073) | − 0.039*** (0.008) | – | − 0.104 (0.065) | − 0.026*** (0.009) | – | − 0.125 (0.064) | − 0.031*** (0.009) | – | − 0.157* (0.068) | − 0.055*** (0.011) | – |
Cyclic triads (030C) | − 0.086 (0.110) | 0.008 (0.011) | – | 0.009 (0.076) | 0.028* (0.014) | – | − 0.072 (0.082) | − 0.027 (0.014) | – | 0.174 (0.102) | 0.114*** (0.023) | – |
GWDSP mixed-star | – | – | − 0.104*** (0.020) | – | – | − 0.044** (0.019) | – | – | − 0.042 (0.023) | – | – | − 0.130*** (0.0268) |
GWDSP in-star | – | – | 0.080*** (0.018) | – | – | 0.023 (0.015) | – | – | 0.032 (0.019) | – | – | 0.086*** (0.024) |
Indegree—popularity | 0.605 (0.353) | 0.450*** (0.052) | 0.526*** (0.065) | 0.997*** (0.266) | 0.662*** (0.066) | 0.462*** (0.049) | 0.605 (0.326) | 0.495*** (0.049) | 0.706*** (0.071) | 1.162*** (0.324) | 0.755*** (0.087) | 0.421*** (0.086) |
Outdegree—popularity | − 0.247 (0.483) | − 0.807*** (0.090) | − 0.156* (0.068) | − 0.687* (0.315) | − 0.957*** (0.097) | − 0.107 (0.055) | − 0.731 (0.416) | − 0.693*** (0.097) | − 0.285*** (0.073) | − 1.190*** (0.382) | − 0.935*** (0.110) | − 0.027 (0.093) |
Outdegree—activity | 0.380*** (0.128) | 0.047 (0.025) | 0.192*** (0.023) | 0.355*** (0.010) | 0.026 (0.028) | 0.237*** (0.023) | 0.091 (0.121) | 0.092*** (0.034) | 0.333*** (0.046) | 0.122 (0.132) | 0.166*** (0.042) | 0.198*** (0.029) |
MST linkages | ||||||||||||
Common language | 0.381 (0.459) | 0.397*** (0.066) | 0.688*** (0.108) | 1.387*** (0.426) | 0.378*** (0.065) | 0.669*** (0.101) | 0.815 (0.438) | 0.350*** (0.077) | 0.629*** (0.138) | 0.714 (0.434) | 0.219*** (0.084) | 0.446*** (0.145) |
Contiguous border | 1.551**** (0.353) | 1.925*** (0.398) | 1.043* (0.513) | 1.162*** (0.331) | 1.566*** (0.364) | 1.344** (0.531) | 0.725 (0.384) | 1.624*** (0.458) | 1.468* (0.678) | 0.516 (0.367) | 1.674*** (0.447) | 1.219 (0.766) |
Same region | 0.325 (0.224) | 0.567*** (0.080) | 1.050*** (0.189) | − 0.154 (0.242) | 0.679*** (0.086) | 0.928*** (0.181) | 0.041 (0.277) | 0.627*** (0.106) | 1.153*** (0.257) | 0.329 (0.225) | 0.626*** (0.105) | 1.251*** (0.262) |
Shared IGO | 0.423 (0.494) | 0.761*** (0.141) | 0.951* (0.417) | 0.143 (0.315) | 0.1545 (0.092) | 0.159 (0.320) | 0.122 (0.314) | 0.252** (0.103) | 0.373 (0.311) | 0.132 (0.198) | 0.552*** (0.115) | 0.212 (0.129) |
GDP – inflows | 0.105 (0.111) | 0.333*** (0.036) | 0.103** (0.043) | − 0.151 (0.088) | 0.033 (0.034) | − 0.109*** (0.036) | − 0.034 (0.098) | 0.051 (0.048) | − 0.123* (0.054) | 0.081 (0.115) | 0.241*** (0.041) | 0.085 (0.057) |
GDP—outflows | 0.132 (0.101) | − 0.148*** (0.036) | − 0.063 (0.040) | 0.115 (0.082) | − 0.121*** (0.043) | 0.017 (0.035) | 0.079 (0.102) | − 0.020 (0.043) | − 0.024 (0.046) | − 0.353*** (0.126) | − 0.237*** (0.059) | − 0.032 (0.047) |
Other controls | ||||||||||||
Old age dep.—inflows | − 0.008 (0.024) | 0.016 (0.010) | 0.003 (0.008) | 0.044* (0.022) | − 0.044*** (0.012) | 0.024*** (0.007) | 0.011 (0.020) | 0.023* (0.011) | − 0.029*** (0.009) | − 0.005 (0.019) | 0.034*** (0.010) | 0.013 (0.008) |
Old age dep.—outflows | − 0.002 (0.023) | − 0.046*** (0.011) | − 0.005 (0.010) | − 0.0224 (0.018) | 0.007 (0.011) | − 0.043*** (0.007) | − 0.051* (0.023) | 0.029* (0.011) | 0.010 (0.011) | − 0.024 (0.023) | − 0.132*** (0.025) | − 0.017 (0.009) |
Population—inflows | − 0.011 (0.191) | − 0.052* (0.026) | 0.017 (0.039) | 0.344*** (0.132) | 0.132*** (0.032) | 0.189*** (0.034) | 0.193 (0.162) | 0.099*** (0.035) | 0.105** (0.045) | 0.137 (0.174) | − 0.046 (0.034) | 0.015 (0.049) |
Population—outflows | 0.058 (0.135) | 0.049 (0.026) | 0.248*** (0.039) | − 0.055 (0.120) | 0.089*** (0.033) | 0.131*** (0.030) | 0.272 (0.156) | − 0.021 (0.031) | 0.138*** (0.044) | 0.492** (0.210) | − 0.132** (0.052) | 0.143*** (0.046) |
Coups—inflows | − 0.123 (6.051) | − 1.374*** (0.266) | − 1.316** (0.551) | 2.141 (4.906) | 0.232 (0.303) | 1.461*** (0.530) | 5.030 (5.328) | − 0.931*** (0.348) | − 0.782 (0.712) | − 4.546 (6.185) | − 0.192 (0.360) | 1.746** (0.730) |
Coups—outflows | − 0.265 (5.349) | 0.217 (0.263) | 0.362 (0.404) | 6.186 (4.624) | 0.293 (0.265) | − 0.120 (0.344) | − 6.936 (6.082) | 0.483 (0.311) | − 0.349 (0.510) | − 13.114 (7.674) | − 0.224 (0.433) | 0.073 (0.507) |
Goodness of fit | ||||||||||||
Indegree or inflows | 0.680 | 0.040 | 0.564 | 0.687 | 0.212 | 0.055 | 0.824 | 0.369 | 0.386 | 0.884 | 0.134 | 0.188 |
Outdegree or outflows | 0.836 | 0.304 | 0.024 | 0.802 | 0.224 | 0.020 | 0.732 | 0.445 | 0.205 | 0.282 | 0.924 | 0.237 |