We kept surveys for which individual information on gender, age, education achievement, and labor income (wage) was available and consistent over the period 2004-2012 for which we have cross-border trade data. We kept the working age population, and dropped individuals below 15 and above 64 years of age.<sup>6</sup> Finally, we kept workers who reported being paid employees rather than self-employed. Wages are reported in various units depending on the country being surveyed. We converted them into monthly full-time equivalent.<sup>7</sup> We exclude the top and bottom 1% of the wage distribution as non-response and under-reporting are typically quite severe among highincome households, and the bottom end of the distribution is likely to suffer from measurement error, misreporting, and omissions to consider financial transfers within the household (such as remittances for instance). There are five categories of educational achievement: no education or incomplete primary, complete primary, incomplete secondary, complete secondary, and postsecondary.

We define skilled workers as workers with at least a complete secondary education.<sup>8</sup> The group of unskilled workers is made of individuals without education (below primary), incomplete primary and complete primary education.<sup>9</sup> Following Katz and Murphy (1992) and Acemoglu and Autor (2011), wages and labor supply are defined in terms of _efficiency units_ by adjusting for the composition of the workforce. We follow Acemoglu and Autor (2011) and define 50 demographic groups of individuals based on the five education categories (no education or incomplete primary education, complete primary education, incomplete secondary education, complete secondary education, and post-secondary education), five job experience groups (0-9 years, 10-19 years, 20-29 years, 3039 years, and more than 40 years), and gender (50=5 education groups _×_ 5 experience groups _×_ 2 genders). We regress the individual log wage on the five education dummies, an experience quartic, the full interaction between the education dummies and the experience quartic, a dummy for

> 6This restriction does not affect our results. Individuals outside the [15-64] years old interval account for on average 4.7% of the population, and 4.6% of the total wage bill.

> 7Wages reported in the various surveys are either daily, weekly, by-weekly, monthly, bi-monthly, quarterly, annually or hourly wages. In the case of hourly wages, we multiplied by the number of hours worked during the day, and by the number of weeks during the month (52 weeks divided by 12 months). In the case where wages are reported on a hourly basis and information on the number of hours is missing, we made the assumption that workers worked 8 hours per day.

> 8In unreported descriptive statistics, we show that the real wages of workers with complete secondary and postsecondary education follow similar trend over time, and so do the wages of workers with below complete secondary education. This similarity in the trends suggest that there is a higher degree of homogeneity within the skilled and unskilled workers rather than between them.

> 9In unreported descriptive statistics, we looked at the evolution of the real wage for each of these education categories. Real wages of workers with complete secondary or post-secondary education followed a similar pattern, quite different from the one for workers with at most incomplete secondary education.

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