  Economists' interests in growth theory have a very long history (Harrod,
1939; Domar, 1946; Solow, 1956; Swan 1956; Mankiw, Romer, and Weil, 1992).
Recently, starting from the neoclassical growth model, Ertur and Koch (2007)
developed the spatially augmented Solow-Swan growth model with the exogenous
spatial weights matrices ($W$). While the exogenous $W$ assumption could be
true only with the geographical/physical distance, it may not be true when
economic/social distances play a role. Using Penn World Table version 7.1,
which covers year 1960-2010, I conducted the robust Rao's score test (Bera,
Dogan, and Taspinar, 2018) to determine if $W$ is endogeonus and used the
maximum likelihood estimation (Qu and Lee, 2015). The key finding is that the
significance and positive effects of physical capital externalities and spatial
externalities (technological interdependence) in Ertur and Koch (2007) were no
longer found with the exogenous $W$, but still they were with the endogenous
$W$ models. I also found an empirical strategy on which economic distance to
use when the data recently has been under heavy shocks of the worldwide
financial crises during year 1996-2010.
