نفوذ و دانش تکنولوژیکی هدایت شده ، سرمایه انسانی و حقوق و دستمزد

By connecting the North–South diffusion and the bias of non-scale technological knowledge and by considering endogenous human capital, we relate the technological-knowledge diffusion with levels, inter-country gaps, growth rates, wage-inequality paths and specialisation patterns. Inter-country gaps fall towards the steady state and the South produces more final goods at the end of the adjustment process. Moreover, it exports relatively more final goods of the type that uses more intensively the relatively abundant human capital and imitated intermediate goods. However, outputs, wages and prices remain different and differences in prices originate the intra-country wage-inequality paths observed in developed and developing countries, since the early 1980s.

Overall, empirical evidence detects, in developed (North) and developing (South) countries, strong technological-knowledge progress, a rise in the proportion of skilled labour, a rise in wage inequality in favour of skilled labour and enlarged international-trade flows, since the early 1980s (e.g., Acemoglu, 2003, Avalos and Savvides, 2006, Berman et al., 1998, Coe and Helpman, 1995, Machin and Van Reenen, 1998, Robertson, 2004 and Zhu and Trefler, 2005). The aim of this paper is to develop an endogenous growth model consistent with these facts. We follow and contribute to two main lines of research: technological-knowledge diffusion growth models (e.g., Grossman and Helpman, 1991); and wage-inequality growth models (e.g., Acemoglu and Zilibotti, 2001). Neither the former nor the latter models attest to all the above trends. The former models ignore wage-inequality analysis. The latter models tend to exclude international technological-knowledge diffusion, are dominated by labour levels and comprise two rival approaches (e.g., Zeira, 2007): (i) the trade approach, anchored in the Stolper–Samuelson theorem (e.g., Leamer, 1998, Wood, 1995a and Wood, 1995b), predicts, however, a rise in relative unskilled wage in developing unskilled abundant countries;1 (ii) the skill-biased technological change (SBTC) approach, rooted in the market-size effect on the technological-knowledge bias that drives wages (e.g., Acemoglu, 2002), predicts, in turn, a rise in relative unskilled technological knowledge and thus in relative unskilled wage in skilled abundant developed countries due to enlarged trade with developing ones. The international technological-knowledge diffusion through trade allows us to connect the two wage-inequality approaches, as is empirically suggested (e.g., Jaumotte et al., 2009). We assume that the North is more productive due to better institutions, higher human capital and innovative R&D (e.g., Aghion and Howitt, 1992). Southern R&D results are imitations of innovations and it has a marginal cost advantage in production (e.g., Grossman and Helpman, 1991). Thus, the South imports intermediate goods, where R&D is applied, that have not yet been imitated and exports those previously imitated;2 i.e., intermediate goods are the vehicle of technological-knowledge diffusion. In line with Mincer (1993) and Lucas (1993), the time spent accumulating human capital is split between school and on-the-job-training (OJT). Relative to skilled human capital, unskilled human capital is OJT intensive and is less productive. The two types of human capital, due to different intensities in the two formation inputs, clearly distinguish two technologies in competitive final goods production. Each type of human capital uses specific quality-adjusted intermediate goods. Thus, in line with the SBTC literature, the substitutability between technologies together with the complementarity between inputs allows us to unde7rstand the path of technological-knowledge bias. By removing (market) scale effects, as recommended by the dominant literature on scale effects (e.g., Jones, 1995a and Jones, 1995b), the technological-knowledge bias is affected by prices, since more expensive goods create higher profits for producers. Therefore, due to technological-knowledge diffusion under trade, when the skilled abundant North exports inputs incorporating its R&D results to an unskilled abundant South, it benefits from the higher prices of goods produced by Southern skilled human capital. The profit opportunities redirect R&D towards inputs that increase the marginal productivity and thus the wage of skilled human capital in the North and, due to technological-knowledge diffusion, in the South. By considering endogenous human capital, economic growth ceases to be only driven by technological-knowledge progress. Moreover, the skill-premium per worker (i.e., the relative wage of workers who accumulate skilled human capital) can rise even when the skill-premium per unit of human capital (i.e., the relative wage of skilled human capital) falls, due to the relative rise in skilled human capital per worker. Furthermore, human-capital accumulation affects the dynamic inter-country specialisation pattern. In trade-theory tradition, there are neither North–South movements of workers nor North–South movements of firms; i.e., wages and interest rates are domestically found. We also assume that trade is always balanced. The pattern of final-goods specialisation is decided by the relative endogenous productivity of each country in each good, which is affected by the path of human capital and quality-adjusted intermediate goods. In the spirit of Vernon (1966), the pattern of intermediate-goods trade is determined by innovative and imitative activities. While before trade the technological knowledge available to the South is domestic, under trade the top quality intermediate goods available internationally embody the North's technological knowledge, which is a static trade benefit to the South. Thus, under trade, inter-country differences in human-capital levels and institutions impose different inter-country prices.3 The higher prices of final goods produced by skilled human capital in the unskilled abundant South redirect R&D towards the complementary intermediate goods — i.e., increase the relative demand for skilled-specific new designs — which boost the relative worldwide supply of skilled-specific intermediate goods and thus the skill premium in both countries. Indeed, as the North–South average relative price of final goods produced by skilled human capital (the one that is relevant under trade) is always higher than the one in the pre-trade North, international trade redirects technological knowledge in favour of intermediate goods used by skilled workers, which relatively boosts their wages in both countries. That is, the path of wages is driven by the operation of the price channel under trade, which engenders more moderate paths for technological-knowledge bias. As a result, the initial Southern level effect, induced by access to top quality intermediate goods, is reverted and the wage-inequality path is milder than in the pre-trade North. Both countries produce, consume and export both types of final goods, since they always possess both types of human capital. The South, which in addition to the level effect also benefits from growth effects, produces more final goods at the end of the adjustment process, since inter-country human-capital and technological-knowledge gaps fall; it exports relatively more final goods of the type that use the relatively abundant human capital more intensively — in line with the Hechscher–Ohlian model. However, inter-country differences in the quality of institutions — i.e., in exogenous productivity — and in human-capital levels always impose lower output and lower wages in the South. Moreover, in line with the Ricardian model, the South produces, consumes and exports imitated intermediate goods. To sum up, a model has been developed, which, for the first time in the literature, combines technological-knowledge diffusion under trade, technological-knowledge bias driven by the price channel and human-capital accumulation in order to generate predictions compatible with all the above-mentioned facts. In Section 2, the paper proceeds to characterise both economies and the international market. In Section 3 we derive the dynamic general equilibrium, we obtain the level, steady-state and transitional-dynamics effects, and we analyse the comparative statics and dynamics resulting from alternative parameters. In Section 4 we present some concluding remarks.

By considering trade between the North innovator and the South imitator, this paper connects the diffusion with the bias of technological-knowledge, and thus relates the diffusion under trade with levels, growth rates, specialisation patterns and wage-inequality paths. This connection is analysed in a model where: (i) mechanisms work through the price of final-goods channel; (ii) technological-knowledge progress and human-capital accumulation drive endogenous growth, and their direction, affected by trade, governs wages and specialisation. The dynamic comparative advantage is thus induced by dynamic versions of both the Ricardian and the Hechscher–Ohlian models. A process of convergence between countries exists, since technological-knowledge and employed human-capital gaps narrow — i.e., during the transitional dynamics the South grows at a higher rate than the North, but the differential falls steadily. In spite of the greater interdependence between countries induced by trade, differences in human-capital levels imply that the convergence in prices is only relative: the Southern relative price of skilled final goods remains higher. Thus, the North–South average relative price of skilled final goods is higher than in the pre-trade North, which increases the relative demand for new skilled designs. In turn, this boosts the relative worldwide supply of skilled intermediate goods. Therefore, the interdependence between countries and the price channel induce more R&D directed at improving skilled technological knowledge than in the pre-trade North, which originates more moderate paths for technological-knowledge bias and intra-country wage inequality. In particular, the level effect on the South is reverted and the path of wage inequality is more moderate than in the pre-trade North. Hence, wage-inequality results can be interpreted relative to skill-biased technological change literature. In that literature, the bias that causes intra-country wage inequality is mainly induced through the market-size channel. In our case, changes in intra and inter-country wage inequality also arise from the technological-knowledge bias, which is governed by the price channel under trade and which spreads from the North to the South. In contrast with the market-size channel, the price-channel process is compatible with the observed wage-inequality path in favour of skilled labour in developed and developing countries. Due to level and growth effects, trade strongly benefits the South. However, due to the gaps in exogenous productivity and in human capital, the steady state levels of output and wages remain different between countries. Indeed, although the level effect strongly favours Southern wages, South–north wage differences remain: in steady state there is maintenance of inter-country wage inequality — i.e., they grow at the same rate — which implies that a dynamic Schumpeterian factor-price equalisation or Samuelson result arises. With regards to the specialisation patterns, we find that: (i) at each time, both countries produce, consume and export both types of final goods, since they always have both types of human-capital; (ii) each country exports relatively more final goods of the type that use the relatively abundant type of human capital more intensively, directly in line with the Hechscher–Ohlian model; (iii) the South (North) produces, consumes and exports imitated (not yet imitated) intermediate goods, directly in line with the Ricardian model; (iv) the South produces more final goods at the end of the adjustment process, since it has become more developed (the technological knowledge and human capital gaps decrease). It is also worth recording the fact that numerical simulations show that the model's qualitative behaviour is similar if the value of each parameter or initial condition at a time is changed relative to its baseline value, where slight differences are attained in the value of the variables in the new steady state. This attests to the stability of the model.