Table 2: Correlation between primary and secondary weights, 1979–2010, in real GDP growth rates<sup>*</sup>

||_P _<sup>_T_</sup>|_P _<sup>_T ′_</sup>|_P _<sup>_F_</sup>|_P _<sup>_F ′_</sup>|_P _<sup>_A_</sup>|_P _<sup>_A′_</sup>|_P _<sup>_M_</sup>|_P _<sup>_M′_</sup>|
|---|---|---|---|---|---|---|---|---|
|_P _<sup>_T †_</sup>|1.000||||||||
|_P _<sup>_T ′‡_</sup>|0.800|1.000|||||||
|_P _<sup>_F_</sup>|0.575|0.674|1.000||||||
|_P _<sup>_F ′_</sup>|0.592|0.758|0.546|1.000|||||
|_P _<sup>_A_</sup>|0.628|0.731|0.362|0.415|1.000||||
|_P _<sup>_A′_</sup>|0.851|0.947|0.769|0.884|0.919|1.000|||
|_P _<sup>_M_</sup>|0.581|0.579|0.289|0.425|0.550|0.730|1.000||
|_P _<sup>_M′_</sup>|0.533|0.318|0.278|0.331|0.090|0.252|0.369|1.000|

* Authors’ calculations, using data from the WDI, DOT, IFS, Global Migration, Patentscope, and NSF databases. Growth rates calculated from GDP data in real 2000 U.S. dollars.

> _†_ Main measures of trade, finance, technology, and migration computed from imports, financial outflows, patent citations, and immigrant stock.

> _‡_ Secondary measures of trade, finance, technology, and migration computed from absorption, bilateral FDI, scientific articles, and skilled labor emigration.

measure, calculated with and without the inclusion of migration, and with both real and PPP growth rates, are reported in Table 3.<sup>12</sup> The computed measures in this case are far more stable, and the two clearest poles to emerge are the United States and China. By and large, however, it appears that in addition to these two economies, a mix of advanced (Germany, Japan, the United Kingdom) and emerging (India, Russia, South Korea) economies share the role of being growth poles for the global economy, at least based on the 2004–08 period.

Table 3 captures several other interesting facts. First, it is important to recognize that the ordering of economies above are not one-for-one matches with economic size. Indeed, several large developed economies—such as Germany and France—appear several notches lower than their economic sizes alone would suggest; likewise, several emerging economies, in particular South Korea and Singapore, assume a greater weight than one would expect by GDP alone. Moreover, some regional heavyweights—such as Egypt and South Africa—do not appear in Table 3, likely because of their relatively small economic size (when measured at the global level), coupled with the fact that their growth spillovers are likely contained within their respective regions.

Finally, the uneven distribution of growth polarity is evident: The top two economies typically account for as much as 80 percent of the world total. This result has an interesting factors.

> 12Migration is problematic for three reasons, which justifies our selective inclusion. First, the data are for the stock of migration, as opposed to the flow measures for the other indicators. Second, migration data are currently only available for one year, 2005. Third, as alluded to earlier, migration may capture not only positive spillover effects from a sending nation, but also the possibility of negative shocks in the sending nation, such as war, natural disasters, or economic crises.

14