NBER Working Papers by Daria Taglioni

Trade is measured on a gross sales basis while GDP is measured on a net sales basis, i.e. value added. The rapid internationalisation of production in the last two decades has meant that gross trade flows are increasingly unrepresentative of the value added flows. This fact has important implications for the estimation of the gravity equation. We present empirical evidence that the standard gravity equation performs poorly by some measures when it is applied to bilateral flows where parts and components trade is important. We also provide a simple theoretical foundation for a modified gravity equation that is suited to explaining trade where international supply chains are important.

This paper provides a minimalist derivation of the gravity equation and uses it to identify three common errors in the literature, what we call the gold, silver and bronze medal errors. The paper provides estimates of the size of the biases taking the currency union trade effect as an example. We generalize Anderson-Van Wincoop's multilateral trade resistance factor (which only works with cross section data) to allow for panel data and then show that it can be dealt with using time-varying country dummies with omitted determinants of bilateral trade being dealt with by time-invariant pair dummies.