a positive and significant sign, while its linear term is not significant. The result suggests that the world market share rises increasingly with HHI. On the other hand, the linear and squared CR $ (CR^{2}) $ are both insignificant.

One of the possible explanations for the above results is that the sample involves some “international oligopoly” industries such as tractor, automobile, automobile tires, sheet glass and bearing (for example Carr and Collis [2011]). It is because if oligopolists in a Japanese industry are responsible for a larger share in its oligopolistic international market as well, then the Japanese industry is likely to have a larger world export share. In such case, there may be a positive relationship between domestic concentration and world export share. This relation may have a disturbing effect in this estimation. We should examine the explanation in more detail in future. Second, firm size ratio $ (FR) $ is of a positive sign and statistically significant, and the effects are stable and robust. Therefore, it is concluded that industries with higher share of large-sized firms (with more than 300 employees) are likely to have larger competitive advantage. But, this finding does not mean that larger firms have greater competitiveness.

Third, both export intensity (EX) and intra-industry trade ratio (ITR) have a positive and significant effect on world export share. Industries with higher export-related ratios may capture the competitive pressures from foreign markets, which in turn lead firms to have higher incentives for improving and strengthening competitiveness.

But, these variables may capture export competitiveness in themselves, suggesting the tautological relation. Therefore, the results should be interpreted carefully.

Fourth, domestic demand growth $ (DG) $ has a positive sign, and is significant, though having less significance in one equation. This result is rather against our a priori expectation because industries with lower domestic demand growth may have the so-called “export-drive” incentive, and are likely to prefer export activity in foreign markets. But, the implication from the finding is that as in higher growth industries firms have more opportunities to expand shares and output in domestic markets, they try to improve cost efficiency and to innovate more. The consequence is expanded competitive advantage in international markets, which leads to a larger world export share. In other words, industries with lower demand growth tend to have a weaker international competitiveness. This interpretation seems to be consistent with the present economic condition.

Fifth, both R&D intensity $ (RD) $ and advertising intensity $ (AD) $ were introduced as a “specific advantage”-driving exports. But, the both factors have no discernible effect on export behavior, being inconsistent with our expectations. It is probably because the variables reflect domestic behavior and do not always capture the relative advantage in international markets compared with overseas.

Sixth, processing intensity (PR) has no definite effect on world export share, suggesting that only processing innovation or Japan-specific value chain system has no sufficient competitive