اثرات خارجی بر رشد بهره وری در صنایع اسپانیایی

The paper discusses the role of externalities in promoting industrial growth in Spanish regions. We try to identify whether the so-called dynamic externalities (technological spillovers) come from outside the industry (Jacobs type externalities) or whether they are generated between firms inside the industry (Marshall–Arrow–Romer or MAR type externalities). Moreover, this study attempts to test the effects of competition on innovation and growth (Porter type external effects). Related to earlier work by the authors on static and dynamic externalities analysis, this paper restricts the analysis to dynamic externalities using productivity, instead of labor. The empirical analysis is based on data from the Spanish Industry Survey from 1978 to 1992 for 26 manufacturing branches. We find evidence of dynamic effects due to specialization (MAR) that depend on the level of this variable. While specialization seems to affect productivity growth negatively, once it reaches a certain level, its effect on growth becomes positive due to knowledge sharing. However, we do not find clear evidence on the presence of diversity (Jacobs) and competition (Porter) externalities.

This paper applies to Spanish manufacturing data the kind of analysis carried out in Glaeser et al. (1992) and Henderson et al. (1995) to find evidence about the role of dynamic externalities1 influencing the growth of economic activities in the territory. However, we have overcome various limitations of these papers: firstly we have used productivity instead of labor to measure industrial growth; secondly we have endogenously derived the indexes that measure external effects. Also, we included capital in the production function based model we use and, finally, we do not focus on a few specific industries but on a full range of industries and regions. The empirical analysis is carried out using up to 26 large industrial branches for the 50 Spanish provinces between 1978 and 1992. In this paper we find mixed evidence on the role of specialization externalities (Marshal–Arrow–Romer or MAR type externalities). If specialization is sufficiently high, it seems to be positive for growth as Henderson (1994) argues. On the other hand, if specialization is low, we find a negative effect on growth, a result that coincides with Glaeser et al. (1992). We do not find clear evidence on the presence of diversity (Jacobs type) and competition (Porter type) externalities. The rest of the paper is organized as follows. In Section 2.1, we elaborate on the notion of externality as it is not obvious what the appropriate definition is. We propose a simple typology that guides the rest of the paper. Section 2.2 derives the indexes used to identify externalities and presents the model from which estimation equations are obtained. Section 3.1 contains a brief description of the data and a discussion of the province–industry trends that emerge after the first exploitation of this data. In Section 3.2 we discuss the specifications used in our empirical search for externalities. The main results are offered in Section 3.3. Finally, Section 4 provides some concluding comments.

In this paper we have attempted to test for the presence and persistence of a variety of externalities that may influence the growth of economic activity in the territory, more precisely industrial productivity growth. Our methodology has followed closely that of Glaeser et al. (1992) and Henderson (1994) although we present here some significant improvements. Firstly, using a wide range of manufacturing branches across the Spanish provinces, we have carried out panel data estimations that eliminate the regional–industrial individual effects. Secondly, we have tried to overcome the limitations that arise when using employment to analyze industrial growth. Instead we have used productivity growth. This is particularly relevant when industrial employment has been falling while value added has been increasing. Thirdly, we present a model where the measures that proxy external effects are derived endogenously. The empirical analysis has been done using data from the Spanish Industry Survey from 1978 to 1992 for 26 manufacturing branches across the 50 Spanish provinces. The evidence presented in the paper suggests that there are dynamic externalities favoring the growth of economic activity as measured by industrial productivity and these are related to the specialization within a region and an industry once a certain level has been reached. However we do not find evidence of the presence of diversity and competition external economies. According to these results technological spillovers take place when there is a high degree of specialization. Firms belonging to a certain industry and located in a given territory benefit from deep specialization that promotes knowledge sharing. This however does not occur if specialization is not sufficiently strong. On the other hand, our evidence on diversity externalities is not conclusive. The positive effect of a larger industrial diversity vanishes when we introduce instrumental variables in order to correct for possible endogeneity problems. Finally, we do not find evidence of the effect that competition has on productivity growth. These results differ from those obtained by, amongst others, Glaeser et al. (1992) and de Lucio et al. (1996), who find that diversity plays a role on growth due to cross fertilization among different industries. On the contrary, they are in line with those obtained by Henderson (1994) who finds evidence of the importance of specialization for growth. The results presented here are robust to whichever variable is used to proxy industry growth: employment or value added, as in previous contributions, or productivity, as it is done in this paper.