Figure 1.
Major global migration stocks and net migration of the 2000 census.
Any migrant stock of 600,000 people or more is shown. Units are in millions of migrants. Each country is designated as either a net immigration (blue) or net emigration (tan) country. The centroid of Malaysia is placed in the South China Sea between the two main halves of the country in order to make the connections from Indonesia to Malaysia and from Malaysia to Singapore visible. French Guyana is treated as a territory of France and so reflects the net migration of France.
Table 1.
Major migration stocks for 2000 census round are shown for any link greater than 600,000 migrants.
Figure 2.
Characteristics of human migration network.
(A) Cumulative undirected degree distribution of 1960 (dashed) and 2000 (solid). Plots for all other decades (not shown) progressed from the 1960 line to the 2000 line with time. The number of countries considered remains constant with time and therefore sets an upper limit on k. (inset of A) Log of Source strength as a function of the log of source degree for the 2000 census round. Exponent values remained consistently ∼3 for all census rounds. (B) Total strength s and connectance (i.e. percentage of possible undirected connections) over time. (C) Degree of nearest neighbor, knn, as a function of undirected degree for each country in the 2000 census round with moving average line. (D) Network transitivity and average path length over time. (inset of D) Average source strength per source degree (thousands of people per degree) over time.
Table 2.
List of top 15 migrant source (sending) countries for 1960, 1980 and 2000 showing the number of people originating from that country (stock) and the percent of the total international migration stock for that census round.
Figure 3.
Community maps and mutual information.
(A–C) The color scale indicates the strength of modularity within a community decreasing from top to bottom. As another symptom of the ongoing globalization, the global modularity of the community structures slightly decreases with time: 0.62 in 1960; 0.61 in 1970 and 1980; 0.60 in 1990; and 0.57 in 2000. Similarly, the ratio between the internal and total fluxes slowly decreases in time: 0.80 in 1960; 0.81 in 1970; 0.76 in 1980; 0.75 in 1990 and 2000. (D) The agreement between migrant communities and communities defined on the basis of religion (•), language (+) or population-based gravity models (x) was evaluated using mutual information as a measure of non-linear correlation [29].
Table 3.
Normalized mutual information between the community structures in different decades.