  The expansion of global production networks has raised many important
questions about the interdependence among countries and how future changes in
the world economy are likely to affect the countries' positioning in global
value chains. We are approaching the structure and lengths of value chains from
a completely different perspective than has been available so far. By assigning
a random endogenous variable to a network linkage representing the number of
intermediate sales/purchases before absorption (final use or value added), the
discrete-time absorbing Markov chains proposed here shed new light on the world
input/output networks. The variance of this variable can help assess the risk
when shaping the chain length and optimize the level of production. Contrary to
what might be expected simply on the basis of comparative advantage, the
results reveal that both the input and output chains exhibit the same
quasi-stationary product distribution. Put differently, the expected proportion
of time spent in a state before absorption is invariant to changes of the
network type. Finally, the several global metrics proposed here, including the
probability distribution of global value added/final output, provide guidance
for policy makers when estimating the resilience of world trading system and
forecasting the macroeconomic developments.
