metadata: authors: 0: author: Hakobyan,Shushanik
1: author: Lederman,Daniel
count: World
docna: 0: docna: Factor endowments, technology, capital
            mobility and the sources of comparative advantage in manufacturing
docty: Policy Research Working Paper
subtopic: Construction Industry,Oil Refining & Gas Industry,Common Carriers Industry,Food & Beverage Industry,General Manufacturing,Pulp & Paper Industry,Plastics & Rubber Industry,International Trade and Trade Rules,Energy and Mining,Business Cycles and Stabilization Policies
teratopic: International Economics and Trade
abstracts: cdata!: Using data on net exports and factor
            endowments for more than 100 countries, this paper studies
            the relationship between factor endowments and comparative
            advantage in 28 manufacturing sectors between 1975 and 2010.
            The authors allow for systematic technological differences
            across countries, including differences in factor
            intensities across countries with different ratios of
            skilled labor over unskilled labor. Capital seems to be a
            source of comparative disadvantage in manufacturing, and
            skilled labor is a source of comparative advantage in the
            global sample. However, skilled labor is a source of
            comparative disadvantage in economies with low human
            capital, whereas it is a source of comparative advantage in
            the sample of countries with high human capital. The authors
            attribute this heterogeneity to the rise of capital mobility
            across countries, particularly since the mid-1990s.
repnme: repnme: Factor endowments, technology, capital
            mobility and the sources of comparative advantage in manufacturing
display_title: Factor endowments, technology,
            capital mobility and the sources of comparative advantage in manufacturing
listing_relative_url: /research/2016/08/26628743/factor-endowments-technology-capital-mobility-sources-comparative-advantage-manufacturing
topicv3: Transport Equipment m1326014 1812,Manufacturing Sectors m1326521 1281,Trade m1326924 698,Iron m1503514 2931,Petroleum Industry m1583790 4710
publishtoextweb_dt: 2016-08-03T00:00:00Z
historic_topic: International Economics and Trade
no_of_pages: 31
author_keys: 0: author_key: 780478
1: author_key: 125180
model_extractions: WPS7777 Policy Research Working Paper 7777 Factor Endowments, Technology, Capital Mobility and the Sources of Comparative Advantage in Manufacturing _Shushanik Hakobyan Daniel Lederman_ Latin America and the Caribbean Region Office of the Chief Economist August 2016
Policy Research Working Paper 7777

# **Abstract**

Using data on net exports and factor endowments for more than 100 countries, this paper studies the relationship between factor endowments and comparative advantage in 28 manufacturing sectors between 1975 and 2010. The authors allow for systematic technological differences across countries, including differences in factor intensities across countries with different ratios of skilled labor over unskilled labor. Capital seems to be a source of comparative disadvantage in manufacturing, and skilled labor is a source of comparative advantage in the global sample. However, skilled labor is a source of comparative disadvantage in economies with low human capital, whereas it is a source of comparative advantage in the sample of countries with high human capital. The authors attribute this heterogeneity to the rise of capital mobility across countries, particularly since the mid-1990s.

This paper is a product of the Office of the Chief Economist, Latin America and the Caribbean Region. It is part of a larger effort by the World Bank to provide open access to its research and make a contribution to development policy discussions around the world. Policy Research Working Papers are also posted on the Web at http://econ.worldbank.org. The authors may be contacted at dlederman@worldbank.org.

_The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about development issues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry the names of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank and its affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent._ Produced by the Research Support Team
Factor Endowments, Technology, Capital Mobility and the Sources of Comparative Advantage in Manufacturing<sup>_∗_</sup> Shushanik Hakobyan Daniel Lederman Fordham University World Bank .

**JEL Classifications** : F11; F14

**Keywords** : Factor Endowments; Rybczynski; Specialization; Productivity

> _∗_ The authors gratefully acknowledge financial support from the World Bank’s Research Support Budget and from the Office of the Chief Economist for Latin America and the Caribbean of the World Bank. The authors thank two anonymous referees who provided comments on the initial research proposal and to Francisco Carneiro for his patience and insightful comments.
# **1 Introduction**

In theory, abundant endowments of labor are associated with specialization in labor-intensive manufacturing, as long as trade costs are not prohibitive. In fact, the success of East Asia’s most dynamic economies is attributed precisely to their ability to integrate into the world economy through the efficient use of the one factor of production that they had in good supply: labor (World Bank, 1993). China’s progress and ability to reduce poverty in large scale and the East Asia region’s quick recovery from the late-1990s economic crisis, for example, have been based to a large extent on a model that relies on importing capital and know-how and exporting goods and services that require a great deal of labor (Gill et al., 2013). On the other hand, some countries such as the Dominican Republic are labor abundant and the economy has grown fast, but poverty and unemployment remained high. This is a very different story from that of East Asia and one that is suggestive that some countries might not be using efficiently their most abundant factor of production.

This paper explores the relationship between factor endowments and comparative advantage. In particular, we test the null hypothesis that the products exported by labor abundant countries are not labor intensive, but rather capital-intensive. In that context, we estimate Rybczynski coefficients for the world and for subsets of countries and test whether Rybczynski coefficients are different across different types of countries. We then use the estimated coefficients to assess whether the countries with a low or high ratio of skilled over unskilled labor have a comparative advantage in products that are capital-intensive or labor-intensive.

This paper studies the factor intensity of tradable industries across countries and over time. It is consistent with two neo-classical theories of international trade, namely Ricardian and factor proportions models. Ricardian theories rely on the assumption that countries differ in production technologies, whereas factor proportions models presume that countries utilize similar technologies in production and thus the patterns of trade of an economy are driven purely by international differences in relative factor abundance. There are two strands of empirical trade literature related to these models. The first one examines the implications 2
of the factor proportions theory under the assumption that all countries can access the same technologies. The second assumes Hicks-neutral technological differences across countries.

Under the first strand, Harrigan (1995) focuses on the production side of the factor proportions model and uses data on manufacturing output and factor endowments for 20 OECD countries during the period 1970-1985. The findings strongly suggest that capital abundance and unskilled labor are sources of comparative advantage in most sectors, but the evidence on the effects of skilled labor (and land) is rather weak.

Schott (2003), on the other hand, investigates whether developed and developing countries specialize in different subsets of products as a result of their differences in factor endowments. Using value-added, capital stock, and employment data from UNIDO for up to 45 developed and developing countries across 28 manufacturing industries (aggregated into HO aggregates based on input intensity) in 1990 he finds that labor abundant countries produced relatively little of the most capital-intensive goods. Batista and Potin (2014) extend Schott’s work to explain the dynamics of industrial specialization over time by examining a panel of 44 developed and developing countries over 1976-2000. They find substantial Rybczynski effect in that countries that accumulate capital produce fewer labor-intensive goods and more capital-intensive goods. They further find that poor labor-abundant countries that accumulate capital diversify their output by moving away from labor-intensive industries to capital-intensive industries, while rich capital-abundant countries that accumulate capital specialize in the production of highly capital-intensive goods.

Romalis (2004) uses a factor proportions model to examine whether it could explain the structure of commodity trade by integrating a multicountry version of the HeckscherOhlin model with Dornbusch et al (1980) model with a continuum of goods and Krugman (1980) model of monopolistic competition and transport costs. His approach assumes no factor intensity reversals and fixed factor shares within industries and across countries. His results corroborate the following two predictions. First, countries tend to capture larger production and trade shares of products that use their abundant factors more intensively.

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Second, countries that rapidly accumulate a factor see their production and export structures systematically shift towards industries that use that factor intensively.

In the second strand of trade literature, Harrigan (1997) was the first to empirically test the factor proportions theory assuming that technological differences across countries are Hicks-neutral and industry specific. He uses manufacturing output shares in GDP and factor endowment data for 10 developed countries across 7 industries (Food, Apparel, Paper, Chemicals, Glass, Metals and Machinery) for the period 1970-1988. The results are roughly consistent with those presented by Leamer (1984, who uses net exports as the proxy for the dependent variable) and Harrigan (1995) and suggest that capital and mediumeducated workers are generally associated with larger manufacturing output shares, while non-residential construction and highly educated workers lead to lower output shares.

The seminal paper by Harrigan (1997) improves substantially upon previous empirical work, but his data shows little cross-country variation as high-income OECD countries have similar factor endowments and sectoral output shares. Harrigan and Zakrajsek (2000) overcome this drawback and exploit the cross-country variation by expanding the sample to include 28 OECD and non-OECD countries and 12 industries over a longer period (19701992). Their evidence is broadly consistent with the neoclassical theory in that human and physical capital abundance raise output in the heavy industrial sectors, while physical capital lowers output in food and apparel-textiles.

In a similar vein, Fitzgerald and Hallak (2004) use a cross-section of 21 OECD countries in 1988 to estimate the effects of factor endowment on the pattern of manufacturing specialization, but allow factor accumulation to respond to productivity. Their results suggest that the failure to control for productivity differences across countries produces biased estimates of the Rybczynski coefficients. Their model generates robust results that explain two-thirds of the observed differences in the pattern of specialization between the poorest and richest OECD countries. Using a similar approach, Redding (2002) concludes that in the short run, common cross-country effects such as technological progress are more important in ex4
plaining observed changes in specialization than factor endowments. Over longer periods, factor endowments become relatively more important and account for most of the observed variation in specialization. This evidence is consistent with the idea that changes in relative factor abundance occur gradually and take time to affect the structure of production.

Morrow (2010) builds on Romalis (2004) to augment the model with Ricardian TFP differences, and estimates the model using panel data across 20 developed and developing countries, 24 manufacturing industries, and 11 years (1985–1995). He finds that both productivity differences and the interaction of factor abundance with factor intensity play a role in determining international specialization patterns with little evidence that relative productivity levels are systematically higher or lower for skilled labor abundant countries in skilled labor intensive sectors. Furthermore, he finds that differences in factor abundance are more potent than differences in Ricardian productivity in determining patterns of specialization.

Our paper contributes to the existing literature in at least two ways. First, we examine a large number of countries with considerable heterogeneity in their endowments of capital, skilled and unskilled labor. The existing literature has focused on mostly homogeneous groups of countries such as OECD countries or a small number of countries due to limited availability of production data. Since we are using trade data, we are able to expand our sample to include more than 100 countries. Second, we allow for the possibility of changes taking place both in export-oriented and import-competing industries, thus controlling for potential general equilibrium effects, by relying on Leamer (1995).

The paper proceeds as follows. Section 2 discusses the empirical strategy and describes the data. The results are presented in Section 3. Section 4 concludes.

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# **2 Estimation Strategy and Data**

## **2.1 Econometric model**

Our approach is grounded in neoclassical theories of international trade, and there is vast academic literature in this vein (Fitzgerald and Hallak, 2004; Schott, 2003; Harrigan, 1997). The empirical relationship between factor accumulation and exports can be due to the adoption of technologies (which determine factor input requirements in production), the overall level of economic efficiency in an economy, or the rate of factor accumulation (i.e., industries employing skilled labor intensive technologies will not emerge in economies with insufficient skilled labor). In turn, technology adoption and factor accumulation can be determined by various economic, social and institutional phenomena. Broadly speaking, the empirical Rybczynski function for a given industry can be specified as follows: where the subscript _i_ represents industries, _c_ countries, and _t_ is the time period, _K_ , _SL_ , _UL_ and _T_ are endowments of capital, skilled labor, unskilled labor and arable land, respectively, the dependent variable _x_ is output or exports, and _γt_ is the year fixed effect. The intercept term captures any other factor of production that is not explicitly included and is industryspecific (we estimate equation (1) for each industry separately). The parameters of interest in equation (1) are the _β_ s, which can be interpreted as the inverse of technologically determined factor input requirements (i.e., the amount of each input required to produce and export one unit of a final good) in a given industry.

To allow for the possibility that changes in the economy take place both in exportoriented and import-competing industries, we control for consumption effects by following Leamer (1995) as follows: 6
where _NXci_ is the net exports of country _c_ in industry _i_ , _Vc_ and _V_<sup>_w_</sup> are the vectors of endowments in country _c_ and in the world, respectively (which could potentially include different numbers of factors of production), _sci_ is the consumption share of industry _i_ in country _c_ in total world consumption of that industry, and _A_ is the input-output matrix, with unit factor requirements as its elements. Hence, our estimating equation is the following: _NXcit_ = _αi_ 0+ _βi_ 1( _Kct−sciK_<sup>_w_</sup> )+ _βi_ 2( _SLct−sciSL_<sup>_w_</sup> )+ _βi_ 3( _ULct−sciUL_<sup>_w_</sup> )+ _βi_ 4( _Tct−sciT_<sup>_w_</sup> )+ _γit_ + _εcit_ In this specification, all variables are observable except for consumption shares. We use the following two approaches to estimate consumption shares and construct the independent variables: (1) We assume homothetic preferences across countries so that we can approximate _sci_ by the ratio of country _c_ ’s consumption to the world consumption, _sci ≈ Cc/Cw_ .

(2) We further allow consumption shares to vary by country’s level of development by assuming that they are a function of country _c_ ’s GDP per capita in year _t_ .

As with most applied economic analysis, there are several concerns worth pointing out. First, the _β_ s can differ across countries within industries due to differences in technology adoption (Cusolito and Lederman, 2009) or due to differences in aggregate economic efficiency (or total factor productivity) which can be seen as a scaling factor for the observed factor endowments. As eluded to above, one of the key assumptions underlying neoclassical trade models where comparative advantage is driven by factor endowments is that technologies are identical across countries. This implies, importantly, that a unit of labor or capital in one country is just as productive as a unit of labor or capital in the United States, for instance. In an attempt to address these estimation challenges, we follow the approach taken in Fitzgerald and Hallak (2004) and use existing estimates of aggregate TFP to adjust each country’s factor endowments by the TFP differential with respect to the US to net out 7
productivity differences across countries.

Another assumption of neoclassical trade models is that the number of goods equals the number of factors of production. The existing literature interprets the constant in the empirical equation as capturing the average effect of all omitted factors of production. The inclusion of country fixed effects consequently is then equivalent to assuming that the number of omitted factors of production can vary across countries. We estimate the model with and without fixed effects (see Fitzgerald and Hallak (2004) for a discussion of this issue).

We are interested in exploring differences in _β_ s between different subsets of countries: high income vs. low income, capital or skilled labor abundant vs. unskilled labor abundant. To account for a common error structure, we interact all the regressors with the indicator variable for the each such group. This is essentially a test of the assumption that all countries utilize the same technologies for each industry (after adjusting for cross-country TFP differentials as in Fitzgerald and Hallak (2004)) or they belong to the same diversification cone.

# **2.2 Data**

The data set used in this paper contains information on net exports in 28 three-digit ISIC manufacturing industries, endowments of capital and arable land, employment of skilled and unskilled workers for a sample of 129 countries over the 1975-2010 period. The Data Appendix provides details on the data set construction and highlights the limitations on the country and time coverage of the sample imposed by data availability. One such limitation is the availability of educational data in five-year increments. Thus, the data set is a panel of countries by industry over 5-year periods, with factor endowments measured at the initial year of each period, and net (gross) exports averaged over 5-year period.

We construct employment of skilled and unskilled workers using population and educational attainment data from Barro and Lee (2010). Skilled labor refers to workers between ages 25 and 64 who completed high school (secondary) education. The data on trade 8
come from UN Comtrade (accessed via WITS), capital stock, total factor productivity and consumption from the Penn World Tables, and arable land from the World Development Indicators (WDI). See the Data Appendix for details.

Table 1 reports the summary statistics for endowments of capital, skilled and unskilled labor, arable land (unadjusted for productivity differences) and total factor productivity in our sample over time (Panel A). Panel B and C report the same statistics for two subgroups: countries with high skilled-unskilled ratio and those with low ratio in 2000. We split the sample into two subgroups by skilled-unskilled labor ratio using the median for this ratio in 2000.<sup>1</sup> The number of countries for which data are available has gradually increased from 45 in 1975 to 107 by 2000, and arguably data for more unskilled labor abundant countries became available in later years. Yet the summary statistics shows that the average number of skilled labor stock exploded over this period. Keeping in mind changing set of countries over the years, the skilled labor endowment for an average country has increased from 7.3 to 25 million, while the unskilled labor endowment of an average country hovered around 30 million. Similar pattern albeit less striking is observed for capital endowment which for an average country stood at 0.9 and 2.2 million US dollars in 1975 and 2010, respectively. Comparing Panel B and C, we see that even through relatively high skilled labor abundant countries tend to have on average larger endowment of skilled labor and smaller endowment of unskilled labor (by construction), much of the changes in skilled labor endowment over time was driven by the group of relatively low skilled labor abundant countries. Skilled labor endowment for an average country in the later group increased from 2.1 million in 1975 to 14 million in 2010, compared to same statistic for the group of relatively high skilled labor abundant countries which only changed from 10 million to 24 million.

Table 2 summarizes sectoral net exports in million US dollars and as a share of GDP in 1975 and 2010. There is significant variation in the sectoral trade patterns within industries

> 1We have chosen year 2000 because of data availability. We have also ranked countries by skilled-unskilled labor ratio in each of the available years and the rank correlation across different years is above 0.98.

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and across industries within countries.

# **3 Results**

Table 3 contains the first set of results, which correspond to the unadjusted Rybczynski equations, sector by sector for each of 28 sectors. The dependent variable is net exports, with independent variables constructed as in equation (2). In turn, Table 4 shows the results from the productivity-adjusted Rybczynski equations where the independent variables are constructed using raw factor endowments multiplied by TFP, as in Fitzgerald and Hallak (2004).

To assess how the productivity adjustment affects the estimated coefficients, we rank industries by factor intensity (from most factor intensive to least) and then compute rank correlations for the specification that includes both country and year fixed effects (from Tables 3 and 4). We find little correlation between the ranking of industries by skilled and unskilled labor intensity (0.33 and 0.58, respectively), whereas the ranking of industries by capital intensity is almost reversed (-0.64) suggesting that adjusting for productivity makes a difference.<sup>2</sup> Therefore, our discussion of results below focuses on the estimates presented in Table 4.

Three sets of results are reported in Table 4: controlling for only year fixed effects, only country fixed effects, and both country and year fixed effects. Recall that country fixed effects are included to allow for the possibility that the number of omitted factors of production varies across countries. The year fixed effects are included to capture any time varying factors common to all countries such as common shocks in any given year or common changes in price levels over time. We use rank correlations to assess the importance of inclusion of country and year fixed effects. The coefficient estimates from Table 4 suggest that the inclusion of year fixed effects does not alter the ranking of industries by their factor intensity, as the

> 2The ranking by land intensity is the least affected by the productivity adjustment, with the rank correlation standing at 0.75.

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rank correlation between the two sets of estimates is close to 0.99. However, the omission of country fixed effects changes the ranking of industries quite a bit. In particular, the rankings are completely independent when industries are ranked by unskilled labor intensity. A quick glance at the estimates from specifications with country fixed effects and with country and year fixed effects in Table 4 also reveals that the two set of estimates are qualitatively the same and we focus our discussion on the latter.

A positive estimated coefficient on, for example, skilled labor for a particular industry means that skilled labor abundance is associated with net exports of that industry, or is a source of comparative advantage. Likewise, a negative coefficient on skilled labor indicates that skilled labor abundance is a source of comparative disadvantage or associated with net imports in that industry.

Generally speaking, the only strong inference is that capital and land are found to be a source of comparative disadvantage in most industries. The coefficients on capital are statistically significant and negative for 11 industries, and positive for only 4 industries, with coefficients for the remaining industries being imprecisely estimated. The coefficients on land are statistically significant and negative for 13 industries and positive for 4 industries. The effect of skilled labor is always positive whenever statistically significant, suggesting that skilled labor abundance is a source of comparative advantage for 6 industries. The effect of unskilled labor is difficult to sign because of imprecisely estimated effects with large standard errors. These results are consistent with findings by Fitzgerald and Hallak (2004) that after adjusting for productivity differences, the coefficient on capital is more often negative than positive.

The above results are based on the assumption of homothetic preferences across countries allowing us to impute the consumption shares. We further assume that consumption shares vary by the income level of countries and include GDP per capita in our preferred specification. Table 5 reports the results from the productivity-adjusted Rybczynski equations that control for income level of the country. The estimates are qualitatively the same as in Table 11
4 and hence we proceed with our preferred specification.

To allow for the possibility of more than one diversification cone, we specify an indicator variable for countries with high skilled-unskilled labor ratio in 2000 and interact it with our factor endowment measures.<sup>3</sup> We augment our main regression with these four interaction terms, and report the results in Table 6. All the regressions include country and year fixed effects. The last two columns indicate whether the difference between estimated coefficients for capital and skilled labor are statistically different from zero across the two groups of countries. For the majority of industries, the estimated coefficients on skilled labor are statistically different between the two groups of countries, while the difference in the estimated coefficients on capital are only statistically different from zero for about half of the industries.

To summarize the results so far, we find strikingly heterogeneous effects of capital, skilled and unskilled labor abundance on net exports across countries with high and low skilled to unskilled labor ratio. There are a variety of reasons that could explain such heterogeneity. First, the restrictions on capital mobility have been gradually removed over time whereas the restrictions on labor mobility still persist. Therefore, it is possible that capital has become more mobile over time flowing to countries where it could complement abundant unskilled labor. This would lead to the coefficient on capital to be similar across two groups of countries as is the case in half of the industries in our sample. Figure 1 shows the foreign direct investment-gross capital formation ratio in high and low/middle income countries over the last 40 years. This ratio was relatively stable for both groups of countries up until the early 1990s, but has grown significantly since then. Additionally, the ratio has been much more volatile for the high income group relative to the low/middle income group. There seems to be a structural break in the series in the early 1990s. To account for the potential changes in capital mobility across countries, a la Jones (2000), we split the sample into preand post-1995 sub-samples. We estimate our preferred specification using these sub-samples

> 3We also explored the possibility of more than one diversification cone by splitting the sample by capitalunskilled labor ratio. The set of countries is similar to that grouped by skilled-unskilled labor ratio, and most importantly the Rybczynski coefficients are qualitatively the same. These results are available upon request.

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and the coefficient estimates on capital and skilled labor for two sets of countries with high and low skilled-to-unskilled labor ratio before and after 1995 are reported in Table 7.

Before 1995 capital was a source of comparative disadvantage in all industries of countries with low skilled-to-unskilled labor ratio (estimates for 10 industries are statistically significant and negative) whereas it was a source of comparative advantage in a handful of industries in countries with high skilled-to-unskilled labor ratio (out of 14 statistically significant coefficients on capital, 9 are positive). Furthermore, the difference between the estimates on capital of the two groups of countries is statistically different from zero for all industries with positive and statistically significant coefficient on capital. However, while the number of industries with a negative coefficient on capital has not changed in countries with low skilled-to-unskilled labor ratio after 1995 (estimates for 9 industries are statistically significant and negative), there are now 4 industries where capital is found to be a source of comparative advantage. In contrast, after 1995 the results are more mixed for countries with high skilled-to-unskilled labor ratio; in about half of the industries for which the estimates are statistically significant, capital is a source of comparative advantage and in the other half it appears to be source of comparative disadvantage. Additionally, the differences between the two groups of countries are no longer as significantly different as before 1995, providing some support for increased capital mobility in later decades.

Yet, the pattern of comparative advantage based on skilled labor became increasingly different across these two groups of countries over time. Before 1995, skilled labor was a source of comparative advantage in almost all industries with statistically significant coefficients across both subsets of countries. After 1995, it continues to be a source of comparative advantage in countries with high skilled-to-unskilled labor ratio, but becomes a source of comparative disadvantage in a large number of industries in countries with low skilled-tounskilled labor ratio.

Another explanation for wide heterogeneity in the estimated coefficients is the possibility that countries with high and low skilled-to-unskilled labor ratios produce different varieties 13
within the same commodity categories, with the former using more capital-intensive technologies than the latter, leading to the patterns of comparative advantage observed in the data. This is consistent with the findings in Schott (2003).

In Table 8 we evaluate the goodness of fit of our preferred estimations for the sample of low human-capital economies and for the sample of high human-capital countries. The first set of columns reports summary statistics for the group of countries with a low skilled-unskilled labor ratio, followed by the high-skill sample. For each group of countries, the table shows the observed average net exports for each industry, the mean regression residuals reported in Table 6 for each group of countries, and the ratio of the mean residual over the observed net exports.

Table 8 suggests that the model does a relatively good job at explaining cross country variation in net exports. Most of the ratios of the average industry-specific residuals over the – observed average net exports are relatively small on average about 0.09% and 0.61% for the sample of low-skill and high-skill economies, respectively. Only for handful industries, the average residuals are larger than 4% relative to net exports; for example, the model overpredicts the size of net exports in Tobacco industry for low-skill economies and in Petroleum refineries and Glass manufacturing in high-skill economies, whereas high-skill economies are observed to have less net exports in Non-ferrous metals than the model predicts. Hence, we conclude that the model with heterogeneous Rybczynski coefficients seems to provide an acceptable set of predictions for both sub-samples.

# **4 Conclusion**

This paper makes two contributions to the literature. First, it extends the empirical literature on the estimation of factor proportions as determinants of international trade patterns to a large set of diverse economies, including developing countries. By relying on trade data, rather than on production data, and by following Leamer (1995), the estimation sample 14
includes more than 100 countries, thus providing richer evidence than the existing literature that relies predominantly on data from high-income economies.

Second, the paper pays special attention not only to the role of Hicks-neutral international technological differences, but also to the role of systematic technological differences across countries with different relative factor endowments. More specifically, the paper provides evidence concerning the differences in Rybczynski coefficients across countries with low and high ratios of skilled labor over unskilled labor.

The resulting evidence seems relevant for understanding global patterns of trade specialization. As in Fitzgerald and Hallak (2004), we find that controlling for Hicks-neutral technological differences across countries is quite important. In particular, capital does not seem to be a "friend" of manufacturing after one controls for international TFP differences that affect the productivity of all factors of production equally. However, skilled labor seems to play an important, favorable role, on average, when one assumes that there are no systematic technological differences across economies with different human capital endowments.

However, the evidence also suggests that allowing for differences in the Rybczynski coefficients across countries changes the picture significantly. Developing economies, with relatively lower endowments of skilled labor, exhibit statistically significantly different coefficients than their high-skill counterparts within industries. In addition, these differences could be associated with the rise of foreign direct investment since the 1990s, when its importance relative to domestic investment rose particularly in low- and middle-income countries. From the viewpoint of low-skill economies, which developed comparative advantage in several manufacturing industries, the evidence implies that export-oriented manufacturing industries do require substantial numbers of unskilled workers relative to skilled workers. In turn, we conjecture that specializing in manufacturing exports that are in part driven by foreign direct investment is unlikely to raise the skilled-labor premium, precisely because these industries seem to be relatively intensive in the use of unskilled labor in economies with relatively low abundance of skilled workers.

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