In this section, we describe briefly four sources of FYR Macedonia data used in the analysis (full details are provided in Appendix A). The data sets each offer detailed information along multiple dimensions (e.g., precisely defined import products, country of origin, date of arrival, etc.). Precision along multiple dimensions allows credible matching across data sets, even though the data lack unique identifiers that would tie the data sets together at the level of an individual import shipment.

The first data set provided by the FVA includes information on the annual sampling plans for 2014 and for 2015, which are the key outcome of the FVA reform and offer strong guidance to FVA border agents regarding the number of certain types of shipments to be sampled during the upcoming year. The shipment types are defined in terms of broad product groups, countries or country groups (e.g., CEFTA countries), the type of import license and the hazard for which the sample is to be tested.<sup>27</sup> For example, the 2014 plan calls for the taking of 12 samples from the product category _bovine meat, fresh or frozen_ originating from EU or European Free Trade Agreement (EFTA) countries at the border post of Tabanovce for the purposes of testing for the hazards of _Salmonella_ , _E.coli_ , and antimicrobial substances. Some of our other data are not available at the level of the border post nor by the hazard, thus for each year we aggregate the sampling plan data by summing over border post and hazard to produce the planned number of shipments to be sampled at the level of a broad product group and a country or country group.

The second data set provided by the FVA, which we designate _the FVA lab sample data set_ , includes information on the shipments from which FVA border agents took samples for the purpose of laboratory testing, along with the outcome of the tested samples for the period 2013-2015. Each row of this data set represents an import shipment from which samples were taken to the laboratory and for which information is recorded on product, name of the border post where it entered, date when the sample was taken for laboratory testing, country of origin, and health or other hazards tested in the laboratory. Since the raw data contain verbal descriptions of products that are not always consistent over time, these had to be aggregated into broad product groups, as will be described below. We use the FVA lab sample data set to calculate the number of shipments with samples taken to laboratory at the broad product group-country of origin-month-year or more aggregated levels. Combining these numbers with the numbers of import shipments from the EXIM data set described next allows calculation of sampling rates (i.e., the share of import shipments from which a sample is taken/sent to a laboratory for testing). We also use the FVA lab sample data set to generate an indicator variable at the shipment level identifying import shipments with samples taken to laboratory that had positive results/irregularities (i.e., that are non-compliant with FVA’s technical standards). We calculate the number of samples taken to laboratory that are non-compliant at the

> 27 The breadth of product and country groups is operationally useful because it allows some discretion by border agents over products that (presumably) pose similar risks.  While more disaggregation would be useful for our analysis, it is not built into the sampling plan so we must conduct much of our analysis at this higher level of aggregation.

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