  We aim to contribute to the literature on product space and diversification
by proposing a number of extensions of the current literature: (1) we propose
that the alternative but related idea of a country space also has empirical and
theoretical appeal; (2) we argue that the loss of comparative advantage should
be an integral part of (testing the empirical relevance of) the product space
idea; (3) we propose several new indicators for measuring relatedness in
product space; and (4) we propose a non-parametric statistical test based on
bootstrapping to test the empirical relevance of the product space idea.
