  A recent paper by Hausmann and collaborators (1) reaches the important
conclusion that Complexity-weighted diversification is the essential element to
predict country growth. We like this result because Complexity-weighted
diversification is precisely the first equation of the Fitness algorithm that
we introduced in 2012 (2,3). However, contrary to what is claimed in (1), it is
incorrect to say that diversification is contained also in the ECI algorithm
(4). We discuss the origin of this misunderstanding and show that the ECI
algorithm contains exactly zero diversification. This is actually one of the
reasons for the poor performances of ECI which leads to completely unrealistic
results, as for instance, the derivation that Qatar or Saudi Arabia are
industrially more competitive than China (5,6). Another important element of
our new approach is the representation of the economic dynamics of countries as
trajectories in the GDPpc-Fitness space (7-10). In some way also this has been
rediscovered by Hausmann and collaborators and renamed as "Stream plots", but,
given their weaker metrics and methods, they propose it to use it only for a
qualitative insight, while ours led to quantitative and successful forecasting.
The Fitness approach has paved the way to a robust and testable framework for
Economic Complexity resulting in a highly competitive scheme for growth
forecasting (7-10). According to a recent report by Bloomberg (9): The new
Fitness method, "systematically outperforms standard methods, despite requiring
much less data".
