This paper takes global manufacturing listed companies from 2010 to 2022 as samples and uses the difference-in-differences(DID)method to empirically examine the impact of the internationalization of ESG standards on t...This paper takes global manufacturing listed companies from 2010 to 2022 as samples and uses the difference-in-differences(DID)method to empirically examine the impact of the internationalization of ESG standards on the trade competitiveness of multinational enterprises and their mechanisms.The research finds that the internationalization of ESG standards significantly enhances the trade competitiveness of multinational manufacturing enterprises,and this effect is dynamic and sustainable.The mechanism analysis indicates that the internationalization of ESG standards exerts its influence through three pathways:reducing enterprise financing costs,promoting technological innovation,and enhancing brand reputation.The heterogeneity analysis shows that this effect is more significant in enterprises from developed countries,high-pollution industries,and larger enterprises.This paper provides micro-level evidence for understanding the economic consequences of the internationalization of ESG standards and offers policy implications for multinational enterprises to cope with the global ESG rule changes and enhance their trade competitiveness.展开更多
This paper focuses on Chengdu and Chongqing’s positioning as important economic center in western China and their evolving into an economic center of national influence.On the one hand,it uses the synthetic differenc...This paper focuses on Chengdu and Chongqing’s positioning as important economic center in western China and their evolving into an economic center of national influence.On the one hand,it uses the synthetic difference-in-differences(SDID)method to analyze the impact of policies since 2011 designed to build Chengdu and Chongqing into an important economic center in western China.On the other hand,it employs the entropy-weighted TOPSIS method to comprehensively evaluate the influences of ten core Chinese cities as economic centers within four major urban agglomerations,as well as conduct an analytical assessment of the Chengdu-Chongqing economic circle from key perspectives such as its capacity to lead,capacity to agglomerate,and capacity to radiate.From a longitudinal historical perspective,both Chengdu and Chongqing have benefited significantly from policies designed to build an important economic center in western China,and which laid a foundation for building an economic center of national influence.From a horizontal regional comparison,among the ten core cities evaluated as economic centers within the four major urban agglomerations,Chengdu and Chongqing ranked in the middle,possessing a moderate but not yet outstanding influence.Consequently,to evolve into an economic center of national influence,the Chengdu-Chongqing economic circle should leverage its relative advantages in connectivity,market size,value chain division of labor,policy attractiveness,and industry development.It can enhance its influence by strengthening the complementarity of its economic resources,overcoming the administrative inertia,accelerating the establishment of a regional innovation system,broadening the scope of its economic radiation,and promoting its comprehensive and all-dimensional opening-up.展开更多
County-to-district conversion(CDC) has restructured the pattern of urban-rural development and influenced the allocation of resources by local governments as well as the urbanization process.However,the impact and mec...County-to-district conversion(CDC) has restructured the pattern of urban-rural development and influenced the allocation of resources by local governments as well as the urbanization process.However,the impact and mechanism of the CDC on China's urban-rural integration development(URID) are not yet clear.Using panel data from 52 county-level cities,districts,and counties in Jiangsu Province of China during 2005–2021,this paper constructed an evaluation system for URID and applied the multi-period difference-in-differences(DID) model to measure the impact of the CDC on URID and identify its primary mechanisms of action.The results demonstrated that the CDC has significantly fostered URID,though with pronounced regional heterogeneity.Specifically,while the CDC facilitated URID in the southern and central Jiangsu Province—regions characterized by high socio-economic development—it exerted a less significant impact in the comparatively underdeveloped northern Jiangsu Province.Mechanistically,the implementation of the CDC promotes equal regional development,enhances rural selfdevelopment capacity,improves environmental quality and living standards,and optimizes urban-rural land allocation and transport networks.Ultimately,this study clarifies the role of the CDC in China,provides insights for achieving URID,and offers a reference for other countries pursuing coordinated urban-rural development.展开更多
The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestratio...The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestration in grasslands remains unclear.Based on panel data from prefecture-level cities in the Yellow River Basin(YRB)from 2000 to 2020,this study explored the effects of the GECP on grassland carbon sequestration in the YRB and its heterogeneity using a time-varying difference-in-differences(TV-DID)model.Subsequently,we predicted changes in carbon sequestration in grasslands under the influence of the GECP from 2021 to 2040 using a simulation.The main conclusions are as follows:First,the implementation of the GECP promoted carbon sequestration in grasslands.This conclusion was validated after conducting a series of robustness tests.Moreover,the effects of the GECP were heterogeneous across different geographical locations,highway densities,and grassland areas.Finally,the simulation results indicated that over the next 20 years,grassland carbon sequestration will generally increase but exhibit cyclical changes.The government should align the principles and objectives of the GECP with local geographic conditions,resource availability,and socio-economic development.It must formulate and implement tailored policies that maximize the ecological protection benefits of the GECP and promote carbon sequestration in the grasslands of the YRB.展开更多
The Yangtze River Delta(YRD)is one of China’s most economically dense regions with the most dynamic county-level economies.The YRD’s success in addressing air pollution at the county level directly affects the ecolo...The Yangtze River Delta(YRD)is one of China’s most economically dense regions with the most dynamic county-level economies.The YRD’s success in addressing air pollution at the county level directly affects the ecological security of the Yangtze River Economic Belt.This study utilizes panel data of 151 counties in the YRD from 2003 to 2022.It regards the expansion of members of the YRD Urban Economic Coordination Council as a quasi-natural experiment.This study analyzes the influence of regional integration on county-level air pollution using the difference-in-differences approach,the synthetic difference-in-differences methodology,and spatial econometrics.Our findings indicate that:(1)regional integration can significantly reduce air pollution at the county level;(2)the environmental impact of regional integration is heterogeneous,influenced by regional differences,administrative constraints,and industrial foundations;and(3)regional integration reduces air pollution through advancing industrial structure and technological innovation,along with spatial spillover impacts.Therefore,policymakers should attach importance to air quality governance in counties,deepen regional integration strategies,optimize industrial structures,enhance technological innovation,and strengthen collaborative environmental governance to continuously promote regional sustainable development.展开更多
The carbon emission trading policy is a key policy for China to achieve its dual carbon goals.This paper aims to examine the emission-reduction effects,transmission mechanisms,and carbon-market efficiency of China’s ...The carbon emission trading policy is a key policy for China to achieve its dual carbon goals.This paper aims to examine the emission-reduction effects,transmission mechanisms,and carbon-market efficiency of China’s carbon-emission trading policy from 2012 to 2023.We adopt the difference-in-differences(DID)model to analyze the effects of policy on emissions,and the empirical results from the DID model confirm that the pilot carbon emission trading policy has significantly reduced carbon emission intensity in pilot areas.Then we use the mediation model to study the transmission mechanism of the pilot carbon emission trading policy,and the mediation analysis demonstrates that the pilot carbon emission trading policy achieves emission abatement through four parallel transmission channels:scientific innovation,energy conservation,clean energy substitution,and industrial structure upgrading.Data envelopment analysis evaluates the carbon market efficiency of China.The result shows that the average carbon market efficiency of pilot areas has improved steadily,particularly from 2012 to 2023,especially in Beijing,Hubei,and Guangdong.Moreover,the efficiency of the national carbon market has shown an upward trend since its 2021 launch;it remains lower than the pilot average,constrained primarily by limited sectoral coverage,which impacts scale efficiency.展开更多
Purpose:In recent decades,with the availability of large-scale scientific corpus datasets,difference-in-difference(DID)is increasingly used in the science of science and bibliometrics studies.DID method outputs the un...Purpose:In recent decades,with the availability of large-scale scientific corpus datasets,difference-in-difference(DID)is increasingly used in the science of science and bibliometrics studies.DID method outputs the unbiased estimation on condition that several hypotheses hold,especially the common trend assumption.In this paper,we gave a systematic demonstration of DID in the science of science,and the potential ways to improve the accuracy of DID method.Design/methodology/approach:At first,we reviewed the statistical assumptions,the model specification,and the application procedures of DID method.Second,to improve the necessary assumptions before conducting DID regression and the accuracy of estimation,we introduced some matching techniques serving as the pre-selecting step for DID design by matching control individuals who are equivalent to those treated ones on observational variables before the intervention.Lastly,we performed a case study to estimate the effects of prizewinning on the scientific performance of Nobel laureates,by comparing the yearly citation impact after the prizewinning year between Nobel laureates and their prizewinning-work coauthors.Findings:We introduced the procedures to conduct a DID estimation and demonstrated the effectiveness to use matching method to improve the results.As a case study,we found that there are no significant increases in citations for Nobel laureates compared to their prizewinning coauthors.Research limitations:This study ignored the rigorous mathematical deduction parts of DID,while focused on the practical parts.Practical implications:This work gives experimental practice and potential guidelines to use DID method in science of science and bibliometrics studies.Originality/value:This study gains insights into the usage of econometric tools in science of science.展开更多
As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Ze...As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Zero Waste City pilot policy on PM_(2.5)concentration offers valuable insights into the policy’s effectiveness and provides a potential model for environmental governance worldwide.This study employs panel data from 293 Chinese cities from 2014 to 2022 to systematically analyze the impact of the Zero-Waste City policy on PM_(2.5)concentration using a difference-in-differences model.The findings indicate that the policy not only directly reduces PM_(2.5)concentration but also indirectly curbs PM_(2.5)emissions by enhancing green innovation and green economic efficiency.Moreover,the policy’s effects are found to be positively moderated by urban energy dependence and digital financial inclusion,while they are negatively moderated by the government debt ratio.Based on these findings,this study suggests that cities should actively develop their digital economy,reduce government debt,promote green innovation,and improve green economic efficiency,as doing so will enhance their implementation of environmental policies and promote sustainable urban development.展开更多
Coal dependence and inefficient decentralized heating have significantly increased China’s energy consumption for winter heating,increasing air pollution and exacerbating the greenhouse effect.In 2017,China implement...Coal dependence and inefficient decentralized heating have significantly increased China’s energy consumption for winter heating,increasing air pollution and exacerbating the greenhouse effect.In 2017,China implemented the Pilot Policy on Clean Winter Heating in Northern China,aiming to achieve high central heating coverage and cleaner energy consumption.Studying the effects of this policy can help promote its implementation and serve as a reference for effective adjustment of the contents in the future.However,few studies have investigated this policy and its carbon reduction effects,and most focus on the provincial or city levels.Therefore,this paper considers the policy’s influence on air pollution and carbon emissions at the county level to provide a precise and comprehensive assessment of the policy effects.We use panel data from 1290 counties in 15 provinces in Northern China from 2014 to 2021,applying a multiperiod difference-in-differences model to quantify the impact of the policy on carbon emissions and air quality in the pilot area.We then conduct a series of tests to demonstrate the robustness of the results and analyze the mechanisms of the policy effects from two perspectives,namely,central heating and natural gas use,through a mediating effect model.Finally,we examine the heterogeneity of policy effects between counties based on geographic location and per capita income levels of rural residents through a moderating effect model.The results reveal that the policy significantly reduces air pollution and carbon emissions in the pilot area by increasing the central heating area and natural gas use.Compared with the central and western regions in the north and areas with low-income rural residents,the policy effects in the eastern regions in the north and areas with high-income rural residents are more pronounced.展开更多
Based on personality trait theory and experiential learning theory,lots of studies have revealed a reverse causal relationship between volunteering and the non-cognitive abilities of college students.Using data from a...Based on personality trait theory and experiential learning theory,lots of studies have revealed a reverse causal relationship between volunteering and the non-cognitive abilities of college students.Using data from a longitudinal survey of college students in Hunan Province,China,this study employed the difference-in-differences method to examine the causal relationship between volunteering and non-cognitive abilities,aiming to determine whether volunteering screens or cultivates the non-cognitive abilities of college students.The findings confirmed the screening effect of volunteering on extraversion and conscientiousness and the cultivating effect on agreeableness.However,there was neither a screening effect nor a cultivating effect on emotional stability and openness.It is indicated that volunteering during college primarily screens the non-cognitive abilities of students through personality trait mechanisms,with a limited cultivating effect on non-cognitive abilities.This highlights the necessity to prompt a re-evaluation of how volunteering fulfills its educational function.展开更多
Amid China’s rapid economic growth,significant regional imbalances persisted.To address this disparity,it is essential to pursue high-quality development by fostering endogenous drivers within poverty-stricken areas....Amid China’s rapid economic growth,significant regional imbalances persisted.To address this disparity,it is essential to pursue high-quality development by fostering endogenous drivers within poverty-stricken areas.In late 2011,the Chinese government introduced a new nationwide regional poverty alleviation and development program.This study examines the macroeconomic impacts and micro-level mechanisms of these policies by leveraging manually compiled policy documents and macro and micro data(county economies,enterprises,and land transactions),using a DID approach.The findings reveal that the program significantly boosted economic growth in poor regions without causing negative spillovers to neighboring or paired-assistance areas.Economic growth in the assisted regions was primarily driven by industrialization,encompassing both scale expansion and efficiency gains.A cost-benefit analysis further confirms substantial economic returns and long-term fiscal sustainability.These results provide important policy implications for refining regional poverty policies and advancing balanced development.展开更多
This study proposes a regression-based estimation method in difference-in-differences settings in the presence of time-varying covariates-a scenario commonly encountered in applications.We impose only a conditional pa...This study proposes a regression-based estimation method in difference-in-differences settings in the presence of time-varying covariates-a scenario commonly encountered in applications.We impose only a conditional parallel trends assumption with timevarying covariates and plausible assumptions on the conditional expectation functions.We show that a family of causal effect parameters is exactly the coefficient estimators from our proposed regressions even in the presence of staggered treatment timing and treatment effect heterogeneity across cohorts,time periods,and covariates.These parameters can be further aggregated to the dynamic treatment effects and the overall effect of being treated.We establish the corresponding asymptotic properties.Simulation studies suggest that our proposed regression-based estimators successfully outperform in estimating the causal parameters.Finally,we apply this method to evaluate the effect of intrastate bank deregulation on income inequality in the United States in the setting of Beck et al.(2010).We find substantially different results based on our proposed method.展开更多
The green credit policy(GCP)is an essential financial policy tool for solving the problem of environmental pollution,and urban energy conservation is an effective way to achieve the goal of carbon neutrality.However,e...The green credit policy(GCP)is an essential financial policy tool for solving the problem of environmental pollution,and urban energy conservation is an effective way to achieve the goal of carbon neutrality.However,existing research has not verified the energy-saving effects of green credit(GC)at the city level.Based on panel data from 283 cities in China,this study aims to investigate whether GC can effectively reduce urban energy intensity(EI),which is an important complement to existing research.In terms of research methods,to better evaluate the effect of the policy and exclude the influence of other relevant factors,this study considers the promulgation of the Green Credit Guideline(GCG)in 2012 as the basic event,uses the difference-in-differences(DID)model to investigate the impact of GC on EI,and discusses the main impact mechanism.The key results are follows.(1)GC can effectively reduce urban EI.(2)Public environmental demand positively regulates the negative correlation between GC and EI.(3)GC reduces EI through three main channels:government support,capital investment,and technological innovation;however,the mechanism of industrial structure has no significant effect.(4)The effect of GC is more significant in areas with large urban scales,low environmental regulation intensity,and high industrial agglomeration.Based on the above results,this study presents puts forward targeted policy recommendations to strengthen the role of GC in urban sustainable development.展开更多
Long-term exposure to fine particulate matters(PM_(2.5))has been associated with respiratory and cardiovascular diseases and the burden are potentially higher in China experiencing heavy air pollution.In this study,we...Long-term exposure to fine particulate matters(PM_(2.5))has been associated with respiratory and cardiovascular diseases and the burden are potentially higher in China experiencing heavy air pollution.In this study,we established the exposure-response association between long-term exposures to PM_(2.5)and lung function and blood pressure in Chinesemiddle-aged and older adults using linearmixed-effects and generalized additive mixedmodels based on 3 waves longitudinal health outcomes data by enrolling 19,988 participants from 121 cities across themainland of China.We also assessed the effect of Clean Air Policy(CAP)based on a quasi-experimental difference-in-differences(DID)design.A 10μg/m^(3)increase in PM_(2.5)concentration was associated with a 7.18(95%confidence interval[CI]:-8.35,-6.02)L/min decrease in PEF(peak expiratory flow)and a 0.72(95%[CI]:0.53,0.90)and a 0.30(95%[CI]:0.18,0.42)mmHg increase in systolic and diastolic blood pressure,respectively.The associations were more pronounced in males and rural areas for PEF,but similar across subgroups for blood pressure.DID results suggested that the effect of CAP on health outcomes were sensitive tomagnitudes of reduction in PM_(2.5).A 5μg/m^(3)reduction in PM_(2.5)or more generally led to 18.70(95%[CI]:0.79,36.61)higher PEF and-2.05(95%[CI]:-3.87,-0.23)lower diastolic blood pressure,respectively,compared to no reduction or increase in exposure.However,the effects were significant only in rural areas.Our analysis support CAP aiming to benefit public health and provides insights to inform future control policy for efficiently decreasing air pollution exposure burden.展开更多
文摘This paper takes global manufacturing listed companies from 2010 to 2022 as samples and uses the difference-in-differences(DID)method to empirically examine the impact of the internationalization of ESG standards on the trade competitiveness of multinational enterprises and their mechanisms.The research finds that the internationalization of ESG standards significantly enhances the trade competitiveness of multinational manufacturing enterprises,and this effect is dynamic and sustainable.The mechanism analysis indicates that the internationalization of ESG standards exerts its influence through three pathways:reducing enterprise financing costs,promoting technological innovation,and enhancing brand reputation.The heterogeneity analysis shows that this effect is more significant in enterprises from developed countries,high-pollution industries,and larger enterprises.This paper provides micro-level evidence for understanding the economic consequences of the internationalization of ESG standards and offers policy implications for multinational enterprises to cope with the global ESG rule changes and enhance their trade competitiveness.
文摘This paper focuses on Chengdu and Chongqing’s positioning as important economic center in western China and their evolving into an economic center of national influence.On the one hand,it uses the synthetic difference-in-differences(SDID)method to analyze the impact of policies since 2011 designed to build Chengdu and Chongqing into an important economic center in western China.On the other hand,it employs the entropy-weighted TOPSIS method to comprehensively evaluate the influences of ten core Chinese cities as economic centers within four major urban agglomerations,as well as conduct an analytical assessment of the Chengdu-Chongqing economic circle from key perspectives such as its capacity to lead,capacity to agglomerate,and capacity to radiate.From a longitudinal historical perspective,both Chengdu and Chongqing have benefited significantly from policies designed to build an important economic center in western China,and which laid a foundation for building an economic center of national influence.From a horizontal regional comparison,among the ten core cities evaluated as economic centers within the four major urban agglomerations,Chengdu and Chongqing ranked in the middle,possessing a moderate but not yet outstanding influence.Consequently,to evolve into an economic center of national influence,the Chengdu-Chongqing economic circle should leverage its relative advantages in connectivity,market size,value chain division of labor,policy attractiveness,and industry development.It can enhance its influence by strengthening the complementarity of its economic resources,overcoming the administrative inertia,accelerating the establishment of a regional innovation system,broadening the scope of its economic radiation,and promoting its comprehensive and all-dimensional opening-up.
基金supported by the National Natural Science Foundation of China (42271252,42230510)。
文摘County-to-district conversion(CDC) has restructured the pattern of urban-rural development and influenced the allocation of resources by local governments as well as the urbanization process.However,the impact and mechanism of the CDC on China's urban-rural integration development(URID) are not yet clear.Using panel data from 52 county-level cities,districts,and counties in Jiangsu Province of China during 2005–2021,this paper constructed an evaluation system for URID and applied the multi-period difference-in-differences(DID) model to measure the impact of the CDC on URID and identify its primary mechanisms of action.The results demonstrated that the CDC has significantly fostered URID,though with pronounced regional heterogeneity.Specifically,while the CDC facilitated URID in the southern and central Jiangsu Province—regions characterized by high socio-economic development—it exerted a less significant impact in the comparatively underdeveloped northern Jiangsu Province.Mechanistically,the implementation of the CDC promotes equal regional development,enhances rural selfdevelopment capacity,improves environmental quality and living standards,and optimizes urban-rural land allocation and transport networks.Ultimately,this study clarifies the role of the CDC in China,provides insights for achieving URID,and offers a reference for other countries pursuing coordinated urban-rural development.
基金supported by the National Natural Science Foundation of China[Grant No.71773091]the Graduate Student Science and Technology Innovation Program of College of Economics and Management[Grant No.JGYJSCXXM202308].
文摘The Grassland Ecological Compensation Policy(GECP)is a large-scale project that has been investing in China since 2011.Despite the significant investment and long duration of the GECP,its impact on carbon sequestration in grasslands remains unclear.Based on panel data from prefecture-level cities in the Yellow River Basin(YRB)from 2000 to 2020,this study explored the effects of the GECP on grassland carbon sequestration in the YRB and its heterogeneity using a time-varying difference-in-differences(TV-DID)model.Subsequently,we predicted changes in carbon sequestration in grasslands under the influence of the GECP from 2021 to 2040 using a simulation.The main conclusions are as follows:First,the implementation of the GECP promoted carbon sequestration in grasslands.This conclusion was validated after conducting a series of robustness tests.Moreover,the effects of the GECP were heterogeneous across different geographical locations,highway densities,and grassland areas.Finally,the simulation results indicated that over the next 20 years,grassland carbon sequestration will generally increase but exhibit cyclical changes.The government should align the principles and objectives of the GECP with local geographic conditions,resource availability,and socio-economic development.It must formulate and implement tailored policies that maximize the ecological protection benefits of the GECP and promote carbon sequestration in the grasslands of the YRB.
基金sponsored by Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project[Grant No.2024ZD1002001]National Social Science Foundation of China[Grant No.24VHQ005],National Natural Science Foundation of China[Grant No.72403050]the Fundamental Research Funds for the Central Universities[Grant No.2-9-2023-039].
文摘The Yangtze River Delta(YRD)is one of China’s most economically dense regions with the most dynamic county-level economies.The YRD’s success in addressing air pollution at the county level directly affects the ecological security of the Yangtze River Economic Belt.This study utilizes panel data of 151 counties in the YRD from 2003 to 2022.It regards the expansion of members of the YRD Urban Economic Coordination Council as a quasi-natural experiment.This study analyzes the influence of regional integration on county-level air pollution using the difference-in-differences approach,the synthetic difference-in-differences methodology,and spatial econometrics.Our findings indicate that:(1)regional integration can significantly reduce air pollution at the county level;(2)the environmental impact of regional integration is heterogeneous,influenced by regional differences,administrative constraints,and industrial foundations;and(3)regional integration reduces air pollution through advancing industrial structure and technological innovation,along with spatial spillover impacts.Therefore,policymakers should attach importance to air quality governance in counties,deepen regional integration strategies,optimize industrial structures,enhance technological innovation,and strengthen collaborative environmental governance to continuously promote regional sustainable development.
基金supported by the National Social Science Fund of China under Grant 25CJL064.
文摘The carbon emission trading policy is a key policy for China to achieve its dual carbon goals.This paper aims to examine the emission-reduction effects,transmission mechanisms,and carbon-market efficiency of China’s carbon-emission trading policy from 2012 to 2023.We adopt the difference-in-differences(DID)model to analyze the effects of policy on emissions,and the empirical results from the DID model confirm that the pilot carbon emission trading policy has significantly reduced carbon emission intensity in pilot areas.Then we use the mediation model to study the transmission mechanism of the pilot carbon emission trading policy,and the mediation analysis demonstrates that the pilot carbon emission trading policy achieves emission abatement through four parallel transmission channels:scientific innovation,energy conservation,clean energy substitution,and industrial structure upgrading.Data envelopment analysis evaluates the carbon market efficiency of China.The result shows that the average carbon market efficiency of pilot areas has improved steadily,particularly from 2012 to 2023,especially in Beijing,Hubei,and Guangdong.Moreover,the efficiency of the national carbon market has shown an upward trend since its 2021 launch;it remains lower than the pilot average,constrained primarily by limited sectoral coverage,which impacts scale efficiency.
基金This work was supported by grants from the National Natural Science Foundation of China,with No.NSFC62006109 and NSFC12031005.
文摘Purpose:In recent decades,with the availability of large-scale scientific corpus datasets,difference-in-difference(DID)is increasingly used in the science of science and bibliometrics studies.DID method outputs the unbiased estimation on condition that several hypotheses hold,especially the common trend assumption.In this paper,we gave a systematic demonstration of DID in the science of science,and the potential ways to improve the accuracy of DID method.Design/methodology/approach:At first,we reviewed the statistical assumptions,the model specification,and the application procedures of DID method.Second,to improve the necessary assumptions before conducting DID regression and the accuracy of estimation,we introduced some matching techniques serving as the pre-selecting step for DID design by matching control individuals who are equivalent to those treated ones on observational variables before the intervention.Lastly,we performed a case study to estimate the effects of prizewinning on the scientific performance of Nobel laureates,by comparing the yearly citation impact after the prizewinning year between Nobel laureates and their prizewinning-work coauthors.Findings:We introduced the procedures to conduct a DID estimation and demonstrated the effectiveness to use matching method to improve the results.As a case study,we found that there are no significant increases in citations for Nobel laureates compared to their prizewinning coauthors.Research limitations:This study ignored the rigorous mathematical deduction parts of DID,while focused on the practical parts.Practical implications:This work gives experimental practice and potential guidelines to use DID method in science of science and bibliometrics studies.Originality/value:This study gains insights into the usage of econometric tools in science of science.
基金The authors declare that fund support was received from National Social Science Fund of China[Grant No.23BJL010].
文摘As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Zero Waste City pilot policy on PM_(2.5)concentration offers valuable insights into the policy’s effectiveness and provides a potential model for environmental governance worldwide.This study employs panel data from 293 Chinese cities from 2014 to 2022 to systematically analyze the impact of the Zero-Waste City policy on PM_(2.5)concentration using a difference-in-differences model.The findings indicate that the policy not only directly reduces PM_(2.5)concentration but also indirectly curbs PM_(2.5)emissions by enhancing green innovation and green economic efficiency.Moreover,the policy’s effects are found to be positively moderated by urban energy dependence and digital financial inclusion,while they are negatively moderated by the government debt ratio.Based on these findings,this study suggests that cities should actively develop their digital economy,reduce government debt,promote green innovation,and improve green economic efficiency,as doing so will enhance their implementation of environmental policies and promote sustainable urban development.
基金supported by the National Social Science Fund of China[Grant No.21BGL181]to Yan Chen.
文摘Coal dependence and inefficient decentralized heating have significantly increased China’s energy consumption for winter heating,increasing air pollution and exacerbating the greenhouse effect.In 2017,China implemented the Pilot Policy on Clean Winter Heating in Northern China,aiming to achieve high central heating coverage and cleaner energy consumption.Studying the effects of this policy can help promote its implementation and serve as a reference for effective adjustment of the contents in the future.However,few studies have investigated this policy and its carbon reduction effects,and most focus on the provincial or city levels.Therefore,this paper considers the policy’s influence on air pollution and carbon emissions at the county level to provide a precise and comprehensive assessment of the policy effects.We use panel data from 1290 counties in 15 provinces in Northern China from 2014 to 2021,applying a multiperiod difference-in-differences model to quantify the impact of the policy on carbon emissions and air quality in the pilot area.We then conduct a series of tests to demonstrate the robustness of the results and analyze the mechanisms of the policy effects from two perspectives,namely,central heating and natural gas use,through a mediating effect model.Finally,we examine the heterogeneity of policy effects between counties based on geographic location and per capita income levels of rural residents through a moderating effect model.The results reveal that the policy significantly reduces air pollution and carbon emissions in the pilot area by increasing the central heating area and natural gas use.Compared with the central and western regions in the north and areas with low-income rural residents,the policy effects in the eastern regions in the north and areas with high-income rural residents are more pronounced.
文摘Based on personality trait theory and experiential learning theory,lots of studies have revealed a reverse causal relationship between volunteering and the non-cognitive abilities of college students.Using data from a longitudinal survey of college students in Hunan Province,China,this study employed the difference-in-differences method to examine the causal relationship between volunteering and non-cognitive abilities,aiming to determine whether volunteering screens or cultivates the non-cognitive abilities of college students.The findings confirmed the screening effect of volunteering on extraversion and conscientiousness and the cultivating effect on agreeableness.However,there was neither a screening effect nor a cultivating effect on emotional stability and openness.It is indicated that volunteering during college primarily screens the non-cognitive abilities of students through personality trait mechanisms,with a limited cultivating effect on non-cognitive abilities.This highlights the necessity to prompt a re-evaluation of how volunteering fulfills its educational function.
基金Supported by the National Natural Science Foundation of China(NSFC)(Grant No.72173131)for“Research on New Trends and Driving Forces in China’s Labor Income Share:A Micro Perspective Based on Enterprise Behavior”the China Postdoctoral Science Foundation(Grant No.2023M743940)for“Research on the Income Distribution Effects of Transport Infrastructure Construction:Theoretical Analysis and Quantitative Assessment”.
文摘Amid China’s rapid economic growth,significant regional imbalances persisted.To address this disparity,it is essential to pursue high-quality development by fostering endogenous drivers within poverty-stricken areas.In late 2011,the Chinese government introduced a new nationwide regional poverty alleviation and development program.This study examines the macroeconomic impacts and micro-level mechanisms of these policies by leveraging manually compiled policy documents and macro and micro data(county economies,enterprises,and land transactions),using a DID approach.The findings reveal that the program significantly boosted economic growth in poor regions without causing negative spillovers to neighboring or paired-assistance areas.Economic growth in the assisted regions was primarily driven by industrialization,encompassing both scale expansion and efficiency gains.A cost-benefit analysis further confirms substantial economic returns and long-term fiscal sustainability.These results provide important policy implications for refining regional poverty policies and advancing balanced development.
基金supported by the Special Project for Training Young Science and Technology Talents in Early Career Development of Jiangxi Province,China(Grant No.20244BCE52087).
文摘This study proposes a regression-based estimation method in difference-in-differences settings in the presence of time-varying covariates-a scenario commonly encountered in applications.We impose only a conditional parallel trends assumption with timevarying covariates and plausible assumptions on the conditional expectation functions.We show that a family of causal effect parameters is exactly the coefficient estimators from our proposed regressions even in the presence of staggered treatment timing and treatment effect heterogeneity across cohorts,time periods,and covariates.These parameters can be further aggregated to the dynamic treatment effects and the overall effect of being treated.We establish the corresponding asymptotic properties.Simulation studies suggest that our proposed regression-based estimators successfully outperform in estimating the causal parameters.Finally,we apply this method to evaluate the effect of intrastate bank deregulation on income inequality in the United States in the setting of Beck et al.(2010).We find substantially different results based on our proposed method.
基金Natural Science Foundation of China(Key Program,No 72133003)Key Projects of Philosophy and Social Sciences Research,Ministry of Education,(Grant No.:22JZD008).
文摘The green credit policy(GCP)is an essential financial policy tool for solving the problem of environmental pollution,and urban energy conservation is an effective way to achieve the goal of carbon neutrality.However,existing research has not verified the energy-saving effects of green credit(GC)at the city level.Based on panel data from 283 cities in China,this study aims to investigate whether GC can effectively reduce urban energy intensity(EI),which is an important complement to existing research.In terms of research methods,to better evaluate the effect of the policy and exclude the influence of other relevant factors,this study considers the promulgation of the Green Credit Guideline(GCG)in 2012 as the basic event,uses the difference-in-differences(DID)model to investigate the impact of GC on EI,and discusses the main impact mechanism.The key results are follows.(1)GC can effectively reduce urban EI.(2)Public environmental demand positively regulates the negative correlation between GC and EI.(3)GC reduces EI through three main channels:government support,capital investment,and technological innovation;however,the mechanism of industrial structure has no significant effect.(4)The effect of GC is more significant in areas with large urban scales,low environmental regulation intensity,and high industrial agglomeration.Based on the above results,this study presents puts forward targeted policy recommendations to strengthen the role of GC in urban sustainable development.
基金supported by the National Institute of Environmental Health Sciences(NIEHS)of United States(No.R00ES027511)the National Natural Science Foundation of China(No.42201303).
文摘Long-term exposure to fine particulate matters(PM_(2.5))has been associated with respiratory and cardiovascular diseases and the burden are potentially higher in China experiencing heavy air pollution.In this study,we established the exposure-response association between long-term exposures to PM_(2.5)and lung function and blood pressure in Chinesemiddle-aged and older adults using linearmixed-effects and generalized additive mixedmodels based on 3 waves longitudinal health outcomes data by enrolling 19,988 participants from 121 cities across themainland of China.We also assessed the effect of Clean Air Policy(CAP)based on a quasi-experimental difference-in-differences(DID)design.A 10μg/m^(3)increase in PM_(2.5)concentration was associated with a 7.18(95%confidence interval[CI]:-8.35,-6.02)L/min decrease in PEF(peak expiratory flow)and a 0.72(95%[CI]:0.53,0.90)and a 0.30(95%[CI]:0.18,0.42)mmHg increase in systolic and diastolic blood pressure,respectively.The associations were more pronounced in males and rural areas for PEF,but similar across subgroups for blood pressure.DID results suggested that the effect of CAP on health outcomes were sensitive tomagnitudes of reduction in PM_(2.5).A 5μg/m^(3)reduction in PM_(2.5)or more generally led to 18.70(95%[CI]:0.79,36.61)higher PEF and-2.05(95%[CI]:-3.87,-0.23)lower diastolic blood pressure,respectively,compared to no reduction or increase in exposure.However,the effects were significant only in rural areas.Our analysis support CAP aiming to benefit public health and provides insights to inform future control policy for efficiently decreasing air pollution exposure burden.
