In recent years, a number of different studies have picked up on the HMS methodology, either expanding or applying it to a new focus.<sup>6</sup> Kleimann (2014) used the HMS methodology partly as a basis to study the coverage and depth of the ASEAN agreement as well as of agreements concluded by individual ASEAN members with third countries. In addition, Kleimann (2014) also attempts to analyze the depth of some WTO+ provisions, i.e. to what extent the PTAs create rules that go beyond the WTO legal status quo.<sup>7</sup> Villalta Puig and Dalke (2016) apply the HMS methodology to analyze the legal enforceability of sanitary and phytosanitary measures (SPS) and technical barriers to trade (TBT) provisions in Canada’s PTAs. Kohl, Brakman and Garretsen (2016) focus on 13 WTO+ and 4 WTO‐X provisions identified by HMS and expand the coverage of preferential trade agreements to 296.<sup>8</sup> Despite some minor differences in the definition of legal enforceability, the coding strategies in HMS and Kohl at al. (2016) are compatible and provide quite similar results when comparing them across US and EU PTAs.

Nevertheless, the HMS approach to the collection and analysis of the content of PTAs is not the only one. The Design of Trade Agreements Database (DESTA) developed by Dür et al. (2014) looks in more detail at the content and depth of specific provisions in PTAs for a very large sample of trade agreements. While coverage is limited to 10 policy areas, the coding covers a number of aspects for each area ranging from the simple inclusion of a chapter in the PTA to details on national treatment or harmonization of policies.<sup>9</sup> The new database presented in this paper covers all PTAs notified to the WTO and in force as of December 2015.<sup>10</sup> This amounts to a total of 279 PTAs signed by 189 countries between 1958 and 2015.<sup>11</sup> The database helps us to better understand the extent to which countries regulate policy areas covered by the WTO in their PTAs, as well as those aspects not regulated by the latter. The database allows for extended research on the evolution of the content and depth of PTAs over time, by region, and by level of development. The central idea is, hence, to provide a picture on deep integration at the global scale. We use economic intuition and statistical methods to develop new measures on the content and the depth of preferential trade agreements.

# b. **Areas covered in the database**

Our approach covers 52 policy areas that are further divided into two groups of 14 WTO “plus” or WTO+ and 38 WTO “extra” or WTO‐X areas.<sup>12</sup> WTO+ provisions in PTAs reconfirm existing commitments and, in some cases, provide for further additional obligations. WTO‐X provisions, on the contrary, refer to policy areas that are not yet regulated by the WTO. A policy area is considered as being “covered” by an agreement if the agreement contains an article, chapter or provision, providing for some form of

> 6 The short overview of studies on PTAs is not exhaustive. The interest here is only to show different approaches that have been developed in the literature.

> 7 In deciding whether a policy area is included in the agreement, HMS count provisions that reconfirm existing obligations and/or add substantive new disciplines as being covered. Hence, there is no distinction between the two scenarios in the final results presented, as coverage gives no further indications on the depth of a provision. In this respect, WTO+ provisions could really be defined as “WTO plus or equal”.

> 8 The PTA coverage in Kohl et al. (2016) also includes agreements that were not notified to the WTO.

> 9 The policy areas covered in Dür et al (2014) are market access, services, investments, intellectual property rights, competition, public procurement, standards, trade remedies, non‐trade issues, and dispute settlement.

> 10 The information on notified and in force preferential agreements comes from the WTO, Regional Trade Agreements Information System (RTA‐IS); http://rtais.wto.org/UI/PublicMaintainRTAHome.aspx.

> 11 The database includes 260 trade agreements and 19 partial scope agreements (PSA).

> 12 See Table 1 for a list of the policy areas. See also Annex A Table A 1 for a more detailed description of each policy and what it covers.

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