(like in the case of the EU) and hence do not permit to investigate the effect of TAs and their provisions. We overcome this limitation by using instead inter-country input-output tables to measure government procurement flows. The drawback of this data source is that we do not observe procurement purchases directly, but we employ constructed data based on national accounts. The use of the empirically successful gravity model aims at filtering out noise and identify central tendency in the data.<sup>6</sup> Our analysis draws extensively from the large literature on the gravity model of trade (Head and Mayer, 2015; Anderson, 2011) to assess the policy determinants of trade flows. In doing so, we do not attempt to develop a fully-fledged theoretical model that explains, for instance, the allocation of public and private expenditures across sectors. Our focus is on the incidence of trade policy, taking aggregate sales and expenditure as given. Owing to the separability between allocation of resources within and across countries that is common to many models of trade, we infer trade costs in a “conditional general equilibrium” setting (Anderson and van Wincoop, 2004), i.e. taking as given the allocations of resources across type of goods and services in the public and private sectors. As Fronk (2014) shows, a gravity-style empirical model can be derived also from the auction framework of McAfee and McMillan (1989) combined with a standard comparative advantage model à la Eaton and Kortum (2002). We rely on this validity of the gravity framework for analyzing bilateral flows in government procurement and estimating measures of home bias. Further, our work expands the literature on the partial equilibrium effects of trade agreements (Baier and Bergstrand, 2007; Bergstrand et al., 2015) and its provisions (Dür et al., 2014; Kohl et al., 2016; Mattoo et al., 2017) by focusing on trade where the public sector is the buyer.<sup>7</sup> When we focus on specific TA provisions on government procurement, we rely on recent work showing how to identify the effect of unilateral trade policy within a structural gravity model (Heid et al., 2021; Sellner, 2019; Beverelli et al., 2018). We isolate provisions, like the pubic sharing of information and statistics, whose application is non-excludable (i.e., conditional on compliance by the member countries, non-member countries benefit as well for construction, and 130 thousand euros for supplies and services). The U.S. Federal Procurement Data System collects contract award data for procurement contracts at the federal level only.

> 6Fajgelbaum and Khandelwal (2016) use similar data from the World Input-Output Database (WIOD) to estimate the parameters of a non-homothetic gravity equation.

> 7A theoretically-consistent estimate of the comparative statics effect of TAs requires to specify the full general equilibrium model because changes in trade costs generally affect the allocation of resources across sectors. Different assumptions on the underlying structure of the economy can lead to a common formulation of the comparative statics effect of a change in trade costs as reviewed by Costinot and Rodriguez-Clare (2015). Egger et al. (2011), for instance, estimate the full trade effect of TAs.

7