Ozgur Tufekci, Dr Associate Professor, Department of International Relations, Karadeniz Technical University
Muharrem Bayrak PhD Candidate, Department of International Relations, Karadeniz Technical University
Hakan Uslu, Dr Associate Professor, Department of Economics and Finance, Samsun University
Abstract
This paper investigates the potential impact of Türkiye on international trade with Middle Corridor (MC) countries, taking into account its geopolitical and strategic role over the past two decades and evaluating how the corridor affects connectivity between partner countries. The study employs a gravity model (GM) to investigate the impact of trade flows on the Turkish economy. Our analysis utilizes a panel dataset spanning from 1990 to 2023. It incorporates a range of estimators, including the Poisson pseudo-maximum likelihood (PPML), the fixed effects (FE) estimator, and the random effects (RE) estimator. The findings obtained from all estimation models demonstrate that the gravity model accurately represents Türkiye’s foreign trade with MC countries. In particular, the findings based on all the estimators suggest a positive correlation between the GDP per capita of importing countries and Türkiye’s exports to the member states of the MC. More precisely, the results of the RE model indicate that a 1% increase in the average per capita gross domestic product of an importer country is associated with a 0.92% increase in exports from Türkiye to that country. The findings also indicated a positive correlation between the religious and linguistic homogeneity of the two countries and their membership in the MC. Overall, our results suggest that enhancing economic relations with the nations involved in the MC presents an advantageous scenario and promises significant policy benefits.
Keywords: Türkiye Middle Corridor gravity model international trade Asia
Introduction
The global economic integration trend is gaining momentum, strengthening interconnections and promoting collaboration among neighboring states or regions. Regional economic and social progress presents novel prospects and obstacles, and economic corridors represent a novel approach for states to engage in collaborative efforts. They aim to foster regional economic collaboration by establishing connections between cities, regions, and nations spanning multiple continents. Government entities need to understand the current growing state of economic corridors clearly. Economic corridors have consistently played a crucial role in linking the economies of a given region. Venables asserts that economic corridors directly and indirectly influence well-being. Kuroda et al. ascertain that in the era of globalization, economic corridors have emerged as crucial pillars of regional economic integration.
With the Belt and Road Initiative (BRI) initiated by China in 2013, there has been increased interest in trade corridors in the literature. Huang argues that the BRI has the potential to reduce transport costs and time significantly, and increase the volume of trade between participating countries. On the other hand, Ascensão et al. highlight the potential harms of the BRI beyond its potential in terms of the need for sustainable development. Regarding the Trans-Caspian International Transport Route (TITR), more commonly known as the Middle Corridor (MC), another project linking Asia to Europe, Kenderdine and Bucsky argue that geopolitical advantages and coordination difficulties among participating countries raise doubts about the project’s potential. A similar concern was recognized by Vinokurov et al., who acknowledge the need for greater coordination between participating countries as well as investment in transport infrastructure.
In a comparative analysis of trade corridors, Baniya et al. highlight that the BRI attracts a greater volume of investment, though the Middle and South Corridors, which are still in their infancy stage, also possess considerable potential. As a result of their comparative analysis, Jakobowski et al. present geopolitical stability, infrastructure quality, and regulatory harmonization as success criteria for trade corridors. Şenol and Erbilen observe that Türkiye, situated at the confluence of the BRI and the Northern and Southern Routes, appears to have enhanced its significance within the Middle Corridor in response to conjunctural shifts such as the Russia-Ukraine conflict and decommissioning of the Nord Stream pipeline. Despite the existing literature on the potential impacts of trade corridors indicating that the impacts and expectations regarding Türkiye have been examined, the analysis of the concrete impact of the MC on Türkiye was found to be incomplete. In contrast to previous narrative studies, this paper will illuminate the concrete impact through a methodological analysis.
Moreover, the intensifying emphasis by governments on international corridors in recent years highlights the pivotal role these corridors play in facilitating trade among their beneficiaries. This essay primarily examines the function of the MC initiative. A variety of factors influence trade, and a corridor can facilitate increased trade among those who stand to gain from it. The gravity model (GM) is a commonly employed economic model for forecasting trade opportunities between nations.10 The model has been utilized in recent studies to analyze economic corridors and assess how much they enhance international trade.
This research employs data such as population, GDP per capita, exchange rates, distance from Türkiye, common language, common religion, coastline, colonial past, shared borders, trade flows, and bilateral trade agreements as inputs for the gravity model from 1990 to 2023 to examine the trade potential trends and patterns across member states of the MC.
This study is organized into six components. The introduction offers a concise summary of the importance of this research. The following section delineates the regional integration process and connectivity alternatives. The third section focuses on TRACECA (Transport Corridor Europe-Caucasus-Asia), as a transport corridor connecting Europe, Caucasus, and Asia. The fourth section deals with the MC initiative and how it serves as a bridge for Eurasian trade.
The final part of this section comprehensively elucidates the gravity model, emphasizing its utilization in evaluating trade prospects. The model specification and data sources used in the study are presented in the fifth section. Section six contains the results of our research, discusses these findings, and provides a concise overview of the study’s critical aspects.
Regional Integration and Connectivity
Regional integration is a complex process in which independent nation-states create shared political, legal, economic, and social institutions to govern collectively. Politically, regional integration entails establishing supranational institutions that possess administrative, legislative, and judicial authority. It also involves transferring policy responsibilities from domestic governance institutions to these supranational bodies. At the economic level, regional integration progresses from a common market alongside national markets to a single market where barriers to the free movement of goods, services, capital, and labor are eliminated. This may be followed by adopting a common or single currency alongside or instead of national currencies. Ultimately, full economic union is achieved, involving the implementation of common macroeconomic and fiscal policies.
According to the liberal intergovernmentalist theory, regional integration is positioned between liberalism and realism. Liberal intergovernmentalism (LI) posits that state preferences are shaped by domestic competition among competing economic interests within society, as opposed to the ideology of liberalism. According to LI, realism suggests that after states develop their preferences, they bargain to safeguard and advance their interests. States also collaborate to create institutions that minimize the costs of transactions, overcome collective action issues, and establish trustworthy commitments. This can be achieved, for instance, by delegating agenda-setting and enforcement powers to supranational agents. The LI literature is situated closer to realism, with a particular focus on the role of national governments in the decisionmaking process. The argument is made that states negotiate in accordance with their self-interest and that the connectivity of states also affects national preferences and bargaining processes.
In this understanding, regional integration is advantageous for states since it enables them to make logical decisions based on their interests while facilitating vertical and horizontal exchanges among themselves. Regional integration creates a sense of connectivity that facilitates the retention of mutual peace, the development of mutual capabilities, and carving out a new self-image and role identity. Connectivity encompasses the physical, institutional, and interpersonal connections that form the fundamental support and enabling mechanisms for achieving economic, political, security, and sociocultural goals, and creating connected communities. Improving regional connectivity is a complex undertaking that will necessitate executing ambitious policy measures at both the national and regional levels.
The concept of connectivity represents a shift from traditional state-centered models to a more complex approach to understanding international politics. Connectivity emphasizes the reach beyond the physical borders of nation-sates, challenging the traditional international agenda. It has become a phenomenon for addressing transnational issues such as climate change, cybersecurity, and global health crises. In particular, the advent of new technologies has enabled the emergence of digital diplomacy and network-based approaches, which are transforming traditional methods.16 This transformation is a consequence of the multifaceted nature of connectivity. The tangible aspect of connectivity is physical connectivity, which encompasses transport networks and major infrastructure projects such as the BRI, TRACECA, and the MC. The intangible aspect reflects the interaction between international organizations, states, and non-state actors.
TRACECA and the BTK Railway Project
The conclusion of the Cold War resulted in the reconciliation of certain Eastern Bloc nations with their former adversaries, specifically the Western Bloc nations. TRACECA (Transport Corridor Europe-Caucasus-Asia) is an example of a transport corridor connecting Europe, Caucasus, and Asia. In May 1993, eight countries (Azerbaijan, Armenia, Georgia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan) convened in Brussels with the backing of the EU to establish a transit corridor connecting Europe to the Central Asian countries by utilizing the Black Sea, the Caucasus, and the Caspian Sea. In 1996-1998, Ukraine, Mongolia, and Moldova became participants in the scheme. Bulgaria, Romania, and Türkiye joined in 2002, and Iran joined in 2009.
Since the early 1900s, geopoliticians have emphasized the construction of many transport corridors across the continent to seize Eurasian geography’s dominance; TRACECA is one of these regional cooperation projects. TRACECA, the result of an effort toward strategic superiority, aims to reduce Russia’s geographical dominance in the region. The inclusion of critical actors, such as the postSoviet Union of Socialist Republics (SSR) and the Commonwealth of Independent States, in particular, has been effective in achieving this aim Considering the route from China to Europe, the TRACECA corridor is a significant advantage for Türkiye’s regionalization efforts. For this reason, Türkiye also supports many new initiatives that will complement TRACECA to enhance existing regionalization efforts, including the Baku-Tbilisi-Kars (BTK) Railway Project. The BTK Railway Project is an essential step in TRACECA, also known as the “Iron Silk Road,” as when the project is completed, a significant portion of trade between Europe and Asia will be carried out via this railway.
The BTK project’s foundation was laid on November 21, 2007, with the participation of the presidents of Türkiye, Azerbaijan, and Georgia. The BTK Railway Project is carried out at the heart of TRACECA to fill the shortcomings under the program’s objective. The main difficulties facing the planned transport infrastructure to be developed for the corridor are congestion in international traffic and border crossing.
All in all, the BTK Railway Project is strategically significant. It connects Baku, Turkmenistan, and China via the Caspian Passage and Türkiye, Bulgaria, Serbia, Hungary, Austria, Switzerland, Germany, France, and the UK through Kars. From a geographical perspective, the railway line runs from China to the UK, making the reference to the “Iron Silk Road” easy to understand. In addition to developing economic relations with the West, from Türkiye’s perspective, developing economic ties with countries in the East is a strategic step, and the BTK plays an essential role in this. According to a report prepared during BTK Railway feasibility studies, in the first year after its completion, one million passengers and 6.5 million tons of cargo will be transported, while the target for the next 20 years is three million passengers and 17 million tons of cargo capacity.
Türkiye, a highly engaged member of TRACECA, has not limited itself to the BTK Railway: it has successfully executed several transport projects, with others nearing completion or in the planning phase. Among these projects is the Kars-Nakhchivan railway project, which aims to extend to Tabriz-TehranZahedan and Islamabad after Nakhchivan. Transportation corridors are of significant geostrategic importance for Türkiye and Russia, which are in regional competition. TRACECA’s geopolitical impact as a transportation corridor that connects Asia with the European continent is to reduce the role of the Russian Federation in global competition. In particular, shortening and facilitating transportation from China to Europe has reduced Russia’s influence in Asia. In addition, the effect of the recent war with Ukraine has made the TRACECA corridor advantageous in terms of security.
TRACECA alone cannot be held accountable for the negative turn in Turkish-Russia relations while talking about TRACECA’s positive contribution to the rising momentum in Turkish-Russian relations until 2015.19 However, Russia’s lack of security in terms of the policies implemented by the EU and the U.S. is starting to result in it pursuing an aggressive policy in today’s conjuncture. The annexation of Crimea following the 2008 Russia-Georgia War, its involvement in Syria, and finally freezing relations with Türkiye are manifestations of this foreign policy perception.
Projects like TRACECA serve as socio-economic development tools for Eurasia. The increase in cooperative initiatives resulting from the forces of globalization and regionalization is crucial for promoting regional cooperation and development, facilitating Eurasia’s integration into the international community, and serving as a model for others. These projects are thought to enhance socio-economic growth in Eurasia and are a significant benchmark for bolstering societal connections and promoting the region’s wealth, peace, and stability.
As a pivotal stakeholder in the implementation of these initiatives, the EU offers financial assistance for the establishment and enhancement of transportation infrastructure, including roads, railways, ports and telecommunication networks, along the TRACECA route, which it views as a crucial gateway to Asia. In 2006, the European Commission allocated €6 million to infrastructure projects in member states. The European Central Bank committed approximately €51 million to 39 technical investment projects. Additionally, the IMF and the World Bank invested €1.7 billion in the construction of ports, roads, and railways in member states. Türkiye, a significant partner country, has also made notable contributions, with €63.9 million invested in 19 projects.
The Middle Corridor: A Bridge for Eurasian Trade
A substantial transformation has occurred in the global trading environment. Countries increasingly seek alternative transport routes due to geopolitical concerns and a greater focus on diversification. Asia and Europe are connected by three primary inland trade routes: the Northern Corridor, which passes through Russia; the Southern Corridor, which passes through Iran; and the Trans-Caspian International Transport Route (TITR), or MC, which passes via Central Asia and the South Caucasus. The ongoing military conflict in Ukraine has resulted in unavoidable spillover effects that have raised concerns about the safety of freight traffic along the Northern Corridor. Additionally, cargo transportation along the Southern Corridor is facing difficulties due to sanctions against Iran in the crisis-prone Middle East. As a result, the MC, which passes through Central Asia, the Caspian Sea, the Caucasus, and into Europe, has gained increased significance. Within this framework, the MC is a prospective catalyst for enhancing connectivity across Eurasia.
…
To read more, please download the article by clicking here, here, or here
…
Endnotes 1 Anthony J. Venables, “Comment on Infrastructure and Regional Cooperation by Haruhiko Kuroda, Masahiro Kawai and Rita Nangia,” in François Bourguignon & Boris Pleskovic (eds.), Rethinking Infrastructure for Development, Washington, D.C.: World Bank, 2007, pp. 261–264. 2 Haruhiko Kuroda, Masahiro Kawai & Rita Nangia, “Infrastructure and Regional Cooperation,” in François Bourguignon & Boris Pleskovic (eds.), Rethinking Infrastructure for Development, Washington, D.C.: World Bank, 2007, pp. 235–259. 3 Yiping Huang, “Understanding China’s Belt & Road Initiative: Motivation, Framework and Assessment,” China Economic Review, Vol. 40 (2016), pp. 314–321. 4 Fernando Ascensão et al., “Environmental Challenges for the Belt and Road Initiative,” Nature Sustainability, Vol. 1, 2018, pp. 206–209. 5 Tristan Kenderdine & Peter Bucsky, “Middle Corridor: Policy Development and Trade Potential of the Trans-Caspian International Route,” Asian Development Bank Institute Working Paper, No. 1268, May 2021, https://www.adb.org/sites/default/files/publication/705226/adbiwp1268.pdf (Accessed: 13.08.2024). 6 Evgeny Vinokurov, “Transport Corridors, Belt and Road Initiative, Eurasian Economic Union and Economic Prosperity across the Eurasian Continent,” in Institute of Russian, Eastern European and Central Asian Studies, CASS & Russian International Affairs Council (eds.), Global Governance in the New Era: Concepts and Approaches, Cham: Springer, 2023, pp. 145–151. 7 Suprabha Baniya et al., “Trade Effects of New Silk Road: A Gravity Analysis,” World Bank Group Policy Research Working Paper, No. 8694, January 2019, https://openknowledge. worldbank.org/server/api/core/bitstreams/8f5520c2-3315-58c5-bb42-23460e90fb70/content (Accessed: 13.08.2024). 8 Jakub Jakobowski et al., The Silk Railroad: The EU-China Rail Connections: Background, Actors, Interests, Warsaw: OSW, 2018. 9 Celal Şenol & Süheyla U. Erbilen, “Analysis of the Impact of the Middle Corridor on Türkiye in terms of Geopolitics and Economy in the OBOR Initiative,” Journal of Geography, Vol. 45 (2022), pp. 161–180. 10 Amparo Baviera-Puig et al., “Comparing Trade Areas of Technology Centres Using ‘Geographical Information Systems,” The Service Industries Journal, Vol. 33, No. 7–8 (2013), pp. 789–801; Emelia Walsund, Geographical Information Systems as a Tool in Sustainable Urban Development, unpublished master’s thesis, Malmö: Malmö University, 2013; Suhas Jadhav & Ishita Ghosh, “Future Prospects of the Gravity Model of Trade: A Bibliometric Review (1993–2021),” Foreign Trade Review, Vol. 59, No. 1 (2023), pp. 26–61; Saleh Shahriar et al., “The Gravity Model of Trade: A Theoretical Perspective,” Review of Innovation and Competitiveness: A Journal of Economic and Social Research, Vol. 5, No. 1 (2019), pp. 21–42. 11 Kunyuan Wanghe et al., “Gravity Model Toolbox: An Automated and Open-Source ArcGIS Tool to Build and Prioritize Ecological Corridors in Urban Landscapes,” Global Ecology and Conservation, Vol. 22 (2020), p. e01012; Oscar Martinez, Jose-Manuel Garcia & Narender Kumar, “The Gravity Model as a Tool for Decision Making: Some Highlights for Indian Roads,” Transportation Research Procedia, Vol. 58 (2021), pp. 333–339; Abdolrasoul Ghasemi, Elnaz Miandoabchi & Shiva Soroushnia, “The Attractiveness of Seaport-Based Transport Corridors: An Integrated Approach Based on Scenario Planning and Gravity Models,” Maritime Economics & Logistics, Vol. 23 (2020), pp. 522–547.
12 S. J. Hix, “Regional Integration,” in Neil J. Smelser & Paul B. Baltes (eds.), International Encyclopedia of the Social & Behavioral Sciences, Oxford: Pergamon Press, 2001, pp. 12922- 12925.
13 Andrew Moravcsik, “Liberal Intergovernmentalism,” Oxford Research Encyclopedia of Politics, August 27, 2020, https://oxfordre.com/politics/view/10.1093/acrefore/9780190228637.001.0001/acrefore-9780190228637-e-1065 (Accessed: 07.07.2024); Andrew Moravcsik, “Liberal Intergovernmentalism and Integration: A Rejoinder,” Journal of Common Market Studies, Vol. 33 (1995), p. 611. 14 Giandomenico Majone, “The Common Sense of European Integration,” Journal of European Public Policy, Vol. 13, No. 5 (2006), pp. 607–626; Frank Schimmelfenning, “Liberal Intergovernmentalism,” in Marianne Riddervold (ed.), The Palgrave Handbook of EU Crises, Cham: Springer, pp. 61–78. 15 Frank Hamilton Hankins, American Sociological Review, American Sociological Society, Michigan: The University of Michigan, 1985, p. 378; Karl Deutsch, The Analysis of International Relations, Englewood Cliffs: Prentice-Hall, 1968, p. 159. 16 “Annex: ASEM Connectivity,” ASEAN, https://asean.org/wp-content/uploads/2017/11/Annex-I.pdf (Accessed: 10.10.2024); Manuel Castells, The Rise of the Network Society, Chichester: Wiley-Blackwell, 2010; Corneliu Bjola & Marcus Holmes, Digital Diplomacy: Theory and Practice, London: Routledge, 2015; Thomas Hale & David Held (eds.), Handbook of Transnational Governance: Institutions and Innovations, Cambridge: Polity, 2011.
17 Peter Frankopan, The New Silk Roads: The Present and Future of World, London: Bloomsbury Publishing, 2018; Robert O. Keohane & Joseph S. Nye, Power and Interdependence, Boston: Longman, 2012. 18 Fabrizio Tassinari, “A Synergy for Black Sea Regional Cooperation: Guidelines for an EU Initiative,” CEPS Policy Brief, No. 105, August 2009, https://www.ceps.eu/download/publication/?id=5333&pdf=1334.pdf (Accessed: 10.07.2024); “The Black Sea Region: New Conditions, Enduring Interests,” Chatham House, January 16, 2009, https://www.chathamhouse. org/sites/default/files/public/Research/Russia%20and%20Eurasia/160109blacksea.pdf (Accessed: 12.07.2024); Ruxandra Ivan, New Regionalism or No Regionalism? Emerging Regionalism in the Black Sea Area, Surrey: Ashgate, 2012. 19 Özgür Tüfekçi “Turkey’s Relations with Russia, Central Asian and the Caucasus States,” in Yaşar Sarı & Seyit Ali Avcu (eds.), Russia, Central Asia and the Caucasia, Eskişehir: Anadolu University Press, 2020, pp. 207–231; Özgür Tüfekçi & Ebru Birinci, “Russian Foreign Policy,” Russia, Central Asia and the Caucasia, Eskişehir: Anadolu University Press, 2020, pp. 61–69; Özgür Tüfekçi & Rahman Dağ, “Whither Global Governance? An Approach to the World Politics,” in Özgür Tüfekçi & Rahman Dağ (eds.), Trends and Transformation in World Politics, London: Rowman, 2022, pp. 137–150. 20 Özgür Tüfekçi, “Bölgesel İşbirliklerinin Türk-Rus İlişkilerine Etkisi: Traceca ve Avrasya Ekonomik Birliği Örnekleri,” TYB Akademi, Vol. 6, No. 17 (2016), pp. 159–172. 21 Mushtaq A. Kaw, “Theorizing EU-TRACECA Relationship in Eurasian Context,” Strategic Analysis, Vol. 43, No. 5 (2019), pp. 418–434; “Investment Projects,” TRACECA, https:// traceca-org.org/en/investments/ (Accessed: 10.10.2024); “Projects,” TRACECA Turkey, https://traceca.uab.gov.tr/projeler-traceca (Accessed: 10.10.2024). 22 Faridun Sattarov, “The Emerging Potential of the Middle Corridor,” Horizons: Journal of International Relations and Sustainable Development, No. 21 (2022), pp. 198–207. 23 Middle Trade and Transport Corridor: Policies and Investments to Triple Freight Volumes and Halve Travel Time by 2030, Washington, D.C.: World Bank, 2023.
24 The figures pertaining to foreign trade volumes for the period and countries examined in the study are presented in the Appendix. 25 “Free Access to Detailed Global Trade Data,” UN Comtrade, https://comtradeplus.un.org/(Accessed: 10.07.2024). 26 “World Development Indicators,” World Bank, https://databank.worldbank.org/source/world-development-indicators (Accessed: 10.07.2024). 27 See Google Maps, https://maps.google.com/ (Accessed: 12.07.2024). 28 “Free Trade Agreements,” Republic of Türkiye Ministry of Trade, https://www.trade.gov.tr/free-trade-agreements (Accessed: 15.07.2024). 29 “Crisis Watch,” International Crisis Group, https://www.crisisgroup.org/crisiswatch?utm_campaign=cw_menu_link (Accessed: 15.07.2024). 30 Jeffrey H. Bergstrand, Understanding Globalization through the Lens of Gravity. Singapore: World Scientific Publishing, 2019. 31 Brad Christenson, “World Trade in Apparel: An Analysis of Trade Flows Using the Gravity Model,” International Regional Science Review, Vol. 17, No. 2 (1994), pp. 151–166; J. E. Anderson, “The Gravity Model,” Annual Review of Economics, Vol. 3, No. 1 (2011), pp. 133–160. 32 Walter Isard, “Location Theory and Trade Theory: Short-Run Analysis,” The Quarterly Journal of Economics, Vol. 68, No. 2 (1954), pp. 305–320. 33 Jan Tinbergen, Shaping the World Economy: An Analysis of World Trade Flows, New York: Twentieth Century Fund, 1962. 34 Luigi Caponi, “Theory of Commercial Gravitational Fields in Economics: The Case of Europe,” Networks and Spatial Economics, Vol. 23, No. 1 (2023), pp. 845–884. 35 Pentti Pöyhönen, “A Tentative Model for the Volume of Trade between Countries,” Weltwirtschaftliches Archiv, Vol. 90, No. 1 (1963), pp. 93–100. 36 James E. Anderson, “A Theoretical Foundation for the Gravity Equation,” The American Economic Review, Vol. 69, No. 1 (1979), pp. 106–116. 37 Jeffrey H. Bergstrand, “The Gravity Equation in International Trade: Some Microeconomic Foundations and Empirical Evidence,” The Review of Economics and Statistics, Vol. 67, No. 3 (1985), pp. 474–481. 38 Thibault Fally, “Structural Gravity and Fixed Effects,” Journal of International Economics, Vol. 97, No. 1 (2015), pp. 76–85. 39 John McCallum, “National Borders Matter: Canada-U.S. Regional Trade Patterns,” American Economic Review, Vol. 85, No. 3 (1995), pp. 615–623. 40 James E. Anderson & Eric van Wincoop, “Gravity with Gravitas: A Solution to the Border Puzzle,” American Economic Review, Vol. 93, No. 1 (2003), pp. 170–192. 41 J. M. C. Santos Silva & Silvana Tenreyro, “The Log of Gravity,” The Review of Economics and Statistics, Vol. 88, No. 4 (2006), pp. 641–658. 42 Elhanan Helpman, Marc Melitz & Yona Rubinstein, “Estimating Trade Flows: Trading Partners and Trading Volumes,” The Quarterly Journal of Economics, Vol. 123, No. 2 (2008), pp. 441–487. 43 Saleh Shahriar, Sokvibol Kea & Lu Qian, “Determinants of China’s Outward Foreign Direct Investment in the Belt & Road Economies: A Gravity Model Approach,” International Journal of Emerging Markets, Vol. 15, No. 3 (2020), pp. 427–445. 44 Menggiu Enkang Li & Yu Chen, “Analysis of China’s Importance in ‘Belt and Road Initiative’ Trade Based on Gravity Model,” Sustainability, Vol. 12, No. 17 (2020), pp. 1–20.
45 Nazir Muhammad Abdullahi et.al, “Examining the Determinants and Efficiency of China’s Agricultural Exports Using a Stochastic Frontier Gravity Model,” Plos One, Vol. 17, No. 9 (2022), p. e0274187. 46 Alper Yılmaz, “Turkish Economy in the Belt Road Initiative: A Gravity Model for International Trade,” Journal of Management and Economies Research, Vol. 20, No. 4 (2022), pp. 1–23. 47 Michael Pfaffermayr, “Gravity Models, PPML Estimation and Bias of the Robust Standard Errors,” Applied Economics Letters, Vol. 26, No. 18 (2019), pp. 1467–1471. 48 Celine Carrere, “Revisiting the Effects of Regional Trade Agreements on Trade Flows with Proper Specification of Gravity Model,” European Economic Review, Vol. 50, No. 2 (2006), pp. 223–247.