The Research On The Influence Mechanism By Which Heterogeneous R&d Investment Influences Firm Productivity

China's macro-economic growth has entered the new normal of medium-to-high speed growth track.In this context,in order to accelerate industrial transformation and upgrading and enhance the competitiveness of the real economy effectively,it is necessary to depend on the innovation-driven development strategy and ensure long-term sustainable productivity growth.To realize these objectives,it is not only need to increase R&D investment and promote investment in strategic emerging industries,but also need to pay close attention to the quality and efficiency of innovation investment.The existing theoretical and empirical research mainly focused on the promoting effect of aggregate R&D investment on productivity improvement and economic growth.But they didn't consider the functional differences of external financial sources and the complementarity of the impact of different R&D investment on productivity from the perspective of R&D investment heterogeneity.They neither studied the possible impact of R&D investment structure on firm productivity and economic growth.This paper studies further basing on the existing research.Firstly,we divide aggregate R&D investment into research investment and experimental development investment.And this paper defines the concept of R&D investment heterogeneity from the perspective of financing characteristics and functional mechanism for productivity.By considering R&D investment heterogeneity in the theoretical framework of the Schumpeter growth model,this paper studies the influence mechanism by which heterogeneous R&D investment influences firm productivity under financing constraints by using mathematical model.On the one hand,this paper considers the liquidity shock of short-term investment and the difference of financing characteristics between research investment and experimental development investment in the model of Aghion et al.(2005,2010).By solving and comparing the marginal rates of technical substitution of research investment and experimental development investment under the condition of perfect financial market with those under the condition of imperfect financial market,this paper analyzes the impact of different external financial sources on enterprises' heterogeneous R&D investment.On the other hand,by referring to the nested constant substitution elasticity model of Kemfert(1998)and considering the difference of functional mechanism for productivity between research investment and experimental development investment,this paper adds the complementarity of the impact of two heterogeneous R&D activities on firm productivity to the model of Aghion et al.(2005,2010).By the derivation method,we get the results of the impact of heterogeneous R&D investment on productivity.Combining with the results of the impact of financing constraints on heterogeneous R&D investment,this paper studies the influence mechanism by which heterogeneous R&D investment influences firm productivity under financing constraints.After analyzing the results,we find that the proportion change between two types of heterogeneous R&D investment caused by low level of financial development negatively affects the growth of firm productivity.And it depends on the level of financial development that whether government R&D subsidy works well.This theoretical research develops the Schumpeter growth model in which R&D investment is the determinant of technological progress and economic growth.In those existing Schumpeter growth models,they mainly study the impact of R&D investment scale but neglect the impact of R&D investment structure change on economic growth arising from R&D investment heterogeneity.This theoretical research makes up for this limitation.Secondly,by integrating the difference of financing characteristics between two types of heterogeneous R&D investment with the functional differences of external financial sources,this paper analyzes the impact of financing constraints on Chinese enterprises' heterogeneous R&D investment and finds that the problem is not the underinvestment in total R&D but the imbalance between research investment and experimental development investment under the financial background of undeveloped financial function.The firm-level productivity is estimated by the method of Olley-Pakes.By using the generalized propensity score matching method and constructing the matching model of R&D-productivity,we obtain the characteristics of the impact of Chinese enterprises' R&D investment on firm productivity by data fitting.Basing on the comparison of enterprises' heterogeneous R&D investment situation from multiple dimensions and the differences of the mechanisms by which heterogeneous R&D activities affect firm productivity,it is supposed that the reason,for which the characteristics of the impact of Chinese enterprises' R&D investment on firm productivity is against the common sense,is the imbalance between research investment and experimental development investment from the phenomenon.Combining these two points,we reveal the influencing path of heterogeneous R&D investment on firm productivity under the situation of financing constraints from the phenomenon.This study considers R&D investment heterogeneity and the imbalance between research investment and experimental development investment caused by the functional differences of external financial sources under the situation of financing constraints.It develops the existing correlational studies on the impact of R&D investment on firm productivity and makes up for the limitation that those studies explain the reason for the counterintuitive relationship between China's R&D investment and productivity only from the intuitional perspective.Finally,this paper verifies the influencing mechanism deduced from the theoretical model hypothesis by considering R&D investment heterogeneity and using a two-step analysis method.In the first step,the impact of different external financial sources on enterprises' heterogeneous R&D investment under financing constraints is proved by using the panel regression model.To avoid the problems of selective bias and endogeneity,this result is tested by the propensity score matching method.In the second step,we construct the generalized propensity score matching model of R-productivity and D-productivity,respectively.By respectively estimating the dose-response functions and the treatment-effect functions for R and D,we obtain the characteristics of the impact of enterprises' heterogeneous R&D investment on firm productivity.This result verifies the negative impact on the growth of firm productivity caused by the proportion change between two types of heterogeneous R&D investment under the condition of low financial development level.This empirical research divides R&D investment into research investment and experimental development.It develops the existing empirical studies on financing constraints,enterprises' R&D investment and productivity.Those studies mainly focus on R&D investment scale but neglect R&D investment heterogeneity.This empirical research makes up for this limitation.This paper provides theoretical foundation for enterprises' innovation strategy that enterprises should not only focus on increasing R&D investment but also further optimize the proportion between the two types of heterogeneous R&D investment in total R&D investment.It also provides theoretical support for policy maker to set out effective R&D subsidy policies and policies which promote the development of scientific and technological finance.