Each record in the Perinorm dataset corresponds to a single national, regional, or international standard. Each observation has information on its title, the history of versions, its international relationship, its classification, the original language, the issuing body, the publication date, the withdraw date (if applies) and a brief description of it. Only those documents classified as European standards (coded as “EN”) in Perinorm are included in the count database.

We use that information to build an inventory of the “stock” of active standards<sup>14</sup> for a given product-year in the electrotechnical sector. As Perinorm classifies standards according to the International Classification of Standards (ICS), standards are matched to products using Blind’s (2004) concordance between ICS classification and SITC revision 2 classification<sup>15</sup> . A standard is considered to be in force for a given year if it was published before or during the year in question and (if applicable) if it was withdrawn after the same year. Amendments to existing standards are counted as additional standards. A standard is considered internationally harmonized if it is “identical” to an existing IEC standard. For instance, European standard EN 61965 delineates the mechanical safety of cathode ray tubes<sup>16</sup> . It was introduced in 2002 and modified in 2003, so it appears as active standard from 2002 on. It is considered as internationally harmonized since it implements IEC standard IEC 61965. This standard applies to SITC 776 which included thermionic, cold and photo–cathode valves, tubes and parts.

The extent of international harmonization varies mainly due to the introduction on new harmonized standards. From the total stock of internationally harmonized standards active in 2007 (1,447), 86% were new standards. The rest are either internationally harmonized standards that were active over the full sample (11 %) or some pre-existing non-harmonized standards that were replaced by harmonized standards (3%).

It is worth noting the limitations of the data set. Even though the count variable is a proxy of the number of standards an exporter should comply with, it is not possible to identify the level of technical complexity among those standards affecting a given product. Previous attempts to include the number of pages of each standard as a proxy for its technical complexity proved unworkable, we believe, as Perinorm records the number of pages of each standard in its original language, which may differ among standards.

Table 3 here

> across EU member countries. Third, as supranational standards are relatively recent, it is more feasible to obtain accurate stock data for them than for national standards.

> 14 The primary variable of interest is the total number of standards with which an exporter’s product should comply during a particular year.

> 15 An advantage of this automatically mapping over the manual mapping used in Czubala et al. (2007) is its transparency and automation. On the other hand, the manual mapping has the benefit of allowing a finer level of product-detail. This advantage might be partly offset by the considerable room for the exercise of the analyst’s judgment.

> 16 Cathode ray tubes are electronic vacuum tubes that use focused electron beams to display images. They are most famous for their use in such things as televisions, computer and radar displays, and automated teller machines.

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