| 研究実績の概要 |
As Dosi.et.al(2018) has shown, the aggregate production growth in an industry APG can be broken down into the effect of productivity growth at the company level (Within) and the effect of market share reorganization (Between): APG = Within + Between + Entry - Exit where Between is decomposed into: Between = Between_cs(B1) + Hetero_in(B1). B1 implies that as more productive and/or heterogeneous firms become, in terms of contributing weight, bigger. While B2 implies that more productive and/or bigger (in terms of contributing weight) firms become more heterogeneous. Thus we verify empirically the relationship: APG= W(Within) + B1 +B2. Firstly, as the pilot experiment, we tested the two industries of cement and machine tools industry by using COSMOS1. The cement industry data employed in our empirical study was extracted from the fiscal year 2001/2006. While the machine tools industry from the fiscal year 2010/2016. Except some special years, due to budget limitation, we used mainly the listed firms to the TSE. We partially incorporated the robot industry into the machine tools industry during the period 2010/19. Summing up, in Japan, the growth in the cement industry decreases as the industrial heterogeneity decreases, as the original expectation is fulfilled. It is noted in the European cement industry that the growth increases as the industrial heterogeneity increases. On the other hand, in the machine tool industry, the tendency may be rather different from the cement industry. But the reason cannot be still confirmed.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
We conducted a temporal experimentation on the hypothesis in the targeted industries in Japan, compared with European results. In the cement industry, the hypothesis seems to be roughly fulfilled both in Japan and Italy. But it is interesting that the industry in Italy is rather steadily growing to keep the expected relationship. While the industry in Japan is stagnant to also keep the relationship inversely. On he contrary, in the machine tool industry, the expected relationship will not necessarily held except for some special years. In our data of the machine industry, the data sometimes contains the robot industry. But we cannot at present say that the incorporation of the robot industry has changed the mode of the machine tool industry. It is simply noted that there are different correlations year by year. By employing the notations in the above, we can finally show the obtained results of the correlation in the concerned periods conducted as follows: (1) Cement industry during the period 2001/2003: APG=-0.001765659 W=-0.002027339 B1=0 0.00026168 B2=-6.234602e^(-13); (2) Machine tools industry (including robot industry) during the period 2010/19: APG=0.1752448 W=0.162507 B1=0 0.01273779 B2=-4.599528e^(-12). Needless to say, the latter results wi be decomposed into several modes of correlations year by year.
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| 今後の研究の推進方策 |
In the above, we have shown that the machine tool industry in Japan does not necessarily fulfill the expected correlation suggested by Dosi.et.al.(2018). Due to the budget limitation, we cannot develop the data analysis to the other periods as well as the other industries except for the cement and machine tool industry. In addition, however, we have purchased the historical analysis of the major corporations of the machine tool industry published by Teikoku Data Bank (TDB C2 Historical Report). By resort to the historical analysis, we can examine why the machine tool industry in Japan could have several modes year by year during the targeted period. Thus we will be able to conclude partially the validity of the effect of the heterogeneity to the industrial aggregate production growth as well as its theoretical implication.
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