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Research in sustainable supply chain management: A review
Tianran Li
Master student in Technology and Operation Management, Faculty of Economics and Business
University of Groningen, Groningen, the Netherlands 2013
Abstract
Purpose - This paper proposes an approach, combining both quantitative and qualitative
studies in three different research fields (manufacturing, logistic and service), to explore research in current years related to sustainable supply chain management (SSCM). Three kinds of sustainability performance (social, environmental and economic) are mentioned to see the academic and practical contributions of other articles. Some future research directions are proposed for other scholars and managers.
Methodology - 118 papers are classified due to the methodologies and research fields.
Further groups have been divided with the consideration of three kinds of performances.
Findings - It presents both academic and practical contributions of papers using different
methodologies and from different research fields. Not only observation of current articles is addressed, but also a systematic and comprehensive literature analysis of current contributions and their propositions for other scholars and practitioner is provided. Furthermore, many future research directions are put forward during the discussion.
Originality/value - This paper proposes a comprehensive literature review of sustainable
supply chain management, classifies these relevant articles by four methodologies and three research fields, identify the academic and practical contributions from these articles, and provides many future research directions by taking three sustainability performance measurements into consideration. This paper provides both other scholars and managers with a guideline that can lead to locate relevant papers in a short time and find their own interests in SSCM.
Keywords SSCM, Analytical, Empirical, Three performance measurements, Research
fields
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1. Introduction
Supply chain management is a hot topic nowadays. Companies are putting more and more effort to develop and operate their supply chains in a more effective and efficient ways. The traditional challenge of managing a good supply chain in a company is to reduce the cost, guarantee the just in time delivery and quick response to the market. However, more and more clients pay attention to the environment-friendly products and the cost of environmental protection raises rapidly. This results in increasing focus on supply chain sustainability by many firms. Therefore, the sustainable factors are often integrated into the supply chain management. In a survey carried out by Supply Chain Management Research (SCMR) in April 2009, the proportion of companies that saw the green resourcing demands as significant to their supply chain grew from 20% to 31%, compared to the survey done in September 2008. This gives a strong and a visual image that sustainable supply chain management plays a remarkable role in the company business. At the same time, scientific interest in sustainable supply chain management is gaining obviously. This can be proved by the large number of relevant papers published in recent years (Seuring & Müller, 2008a). The sustainable supply chain management are introduced and defined as a management which aims at three aspects of sustainable development (economic, environmental and social) through controlling the material and information flows with other companies in the supply chain (Seuring, Sarkis, Müller, & Rao, 2008). The relationship between sustainability and supply chain is explained by building a framework and developing a theory model (Carter & Rogers, 2008). The sustainable supply chain management consists of environmental, social and economic performance. Though, many efforts are put in articles about different sustainability performance in supply chain management; the study of sustainability performance in segregation cannot make an overview of sustainable developments in the whole supply chain management. For this reason, an integrated review for sustainable supply chain management contributes to the initial trigger of this paper.
The integrated review will happens to the articles which put their effort on solving the sustainable issues during the supply chain networks. Different perspectives are reported in these articles for sustainable supply chain management such as building a framework for SSCM or increasing profitability for the company. However, the motivation of this paper is to scan the articles with views of discovering existing contribution to the world and potential future research directions. A systematic literature review is necessary to clarify the significance of sustainable supply chain management. The aims of this paper are addressed as follows:
1) Understanding sustainable development in various areas of the supply chain;
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3) Identifying the gaps existing in the articles and propose possible future research directions for other researchers.
Based on the objectives, a research question is presented as follows:
How sustainable development works in supply chain management for the last ten years? What are the critically similar and different findings/contributions in recent
research?
What aspects have rarely been reached and need to be further discovered?
The answers to questions will benefit to understand the sustainability performance in the supply chain network. In order to answer the research questions precisely and clearly, the author needs to follow some methods to conduct these articles. The methods are developed by firstly seeing what other articles have done and finding the gaps they have not filled. In the following two sections, two methods are identified for organizing the literature review and figuring out the answers.
The first method is by the methodologies these articles used. After screening the articles, many methodologies have found in the research. (Zhu & Cote, 2004) builds a case study that integrates the sustainable supply chain management in an industrial development in a Chinese sugar company. The integration brings the company both economic and environmental performance improvement simultaneously. In the paper by (Zhu, Sarkis, & Geng, 2005), a survey is carried out and completed with hundreds of responses. The finding shows that Chinese companies take more consideration about the sustainable supply chain management due to competitive and market pressure. In the paper by (Gold, Seuring, & Beske, 2010), a quantitative model has been applied to review papers and present data in the fields of sustainable supply chain management. There is a literature review trying to summarize the papers on sustainable supply chain management spanning 13 years through research methodologies like review, case study and surveys (Seuring & Müller, 2008a). Several review papers are found that classify the research by empirical studies (Series 0 in Appendix 5). However few articles review the research by considering both the analytical and empirical studies. So this leads us to the first method: Addressing and contrasting academic and practical contributions of reviewed papers
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important in production and manufacturing area (Liyanage, 2007). Also, sustainability takes consideration in the service area. (Organizations & Weber, 2005) explains how the sustainability is integrated into their policies, products and process by the study of European banks and financial service organizations. At the same time, some researchers are taking place in the logistics area. (Kudla & Klaas-Wissing, 2012) mentions that sustainability plays an essential role in the shipper- logistics area. However few papers make a comprehensive review about sustainable development on all manufacturing, logistics and service fields. It leads to the second method:
Addressing and contrasting academic and practical contributions of reviewed papers within three fields (manufacturing, logistics and service) when analyzing the recent research in supply chain management.
Since (Hoejmose & Adrien-Kirby, 2012) has reviewed a few papers by mentioning both the analytical and empirical studies, but not included the factors of different research fields. This paper is planned to review more papers by taking both the methodologies and research fields into consideration.
In the literature review of (Seuring & Müller, 2008a), the author wipe out the loop supply chain (CLSC)‖ when he collect the articles. However in this paper, ―closed-loop supply chain‖ is included. The relationship between CLSC and SSCM will be investigated.
In the next chapter, these two methods are integrated to help classify the articles from several widely recognized journals. Figures and tables are built to show the distribution of these articles by journals, years and the combined methods. Afterwards, three performance measurements are also integrated to further group these articles in chapter 3. The reviewing of these articles and analysis of their contributions are followed. Then chapter 4 opens a discussion by comparing the similar and different findings from previous analysis. Also, the comparison between this paper and other reviews is provided. Based on the discussion, many research gaps are found, and corresponding future research directions are proposed. In final chapter of this paper, the research and practical implications are talked over. Some limitations of this paper are listed at the end of this paper.
2. Methodology
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which mainly study on SSCM increases in a conspicuous and continuous speed. Therefore, the publication period is limited from 2002 – 2013(June). The papers were found in major management, production and environment journals which are described in Appendix 1. A lot of papers are located in the supply chain management journals because the theme of the supply chain. Many papers come from the cleaner and environmental journals due to the theme of sustainability.
In order to decide what searching terms are needed, some related perspectives on sustainable supply chain management in the articles are listed below:
Green supply chain management is defined as integrating environmental considerations into the inter-organizational application of supply chain management (Sarkis, Zhu, & Lai, 2011).
Environmental Supply Chain Management is a set of policies in supply chain management. These policies are related to the natural environment (Zsidisin & Siferd, 2001).
Corporate social responsibility makes any potential contribution to sustainable development within different firms (Moon, 2007).
Sustainable purchasing and procurement are integrated into sustainable supply chain management (Walker, Miemczyk, Johnsen, & Spencer, 2012).
Reverse logistics is a part of an environmental supply chain perspective and is related to the sustainable development (Tsai & Hung, 2009).
6 Table 2.1 Search terms
Search terms Number of papers
Green Supply chains
Sustainable supply chain management(SSCM) Sustainable development
Environmental supply chain Green practices Sustainable practices Green purchasing Socially procurement Sustainable procurement 45 29 19 14 11 5 4 2 2
Table 2.2 Methodologies of reviewed papers
Methodology Number of papers
Quantitative model 28
Case study 34
Survey 42
Literature review 14
Figure 2.1 indicates the distribution of reviewed papers by different journals. And Appendix 4 shows searched journals with their ABS ranking (2011). Some journals are famous with high ranking and accepted highly by the public such as Journal of Purchasing and Supply Management and journal of supply chain management. But some of them are not as popular as the former ones. Like the journal of cleaner production and resource conservation and recycling, they clearly focus on the field of environment. However, they contribute many papers related to the sustainability for research. Journal of cleaner production even published 26 relevant papers in this field, which is much more than the rest of journals. Figure 2.1 shows us a possible indication that the sustainable supply chain management is not discussed as an extremely main stream topic but strongly mentioned and searched in some specific areas (ex. Environmental, clean and green fields). Because supply chain management involves various activities like resourcing, purchasing and transportation, many relevant papers come from journals like resource conservation and recycling, transportation research and journal of purchasing. It indicates that sustainable supply chain management indeed covers many aspects.
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papers between 2002 and 2012 had increased dramatically from 2 to 41. There has been a remarkable increase in papers talking about SSCM since 2006. The continuous rising trend of relevant references gives an evidence that people’s interest in SSCM becomes higher and higher during current years.
Figure 2.1: Number of reviewed papers by journal
Figure 2.2: Number of reviewed papers per year
0 3 6 9 12 15 18 21 24 27 30
Manufacturing & Service Operations Management European Journal of Operational Research Management Science Production and Operations Management Industrial Management & Data Systems Journal of Operations Management International Journal of Operations & Production Management International Journal of Physical Distribution&Logistics Supply Chain Management: An International Journal Journal of Supply Chain Management Transportation Research Journal of Purchasing and Supply Management Resources, Conservation and Recycling Business Strategy and the Environment International Journal of Production Research International Journal of Production Economics Journal of Cleaner Production
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After classifying, the author wants to have an overview of the distribution situation of all the papers. Figure 2.3 shows the number of articles in each category as a statistic of Appendix 2. It is obvious that a large proportion of papers pay their attentions to the manufacturing part of SSCM. Manufacturing field includes automotive, electronic, chemical, food and other industries. These kinds of industries have covered large scale of activities from purchasing raw materials, producing products, distribution, sales and even reverse logistics. So the range of manufacturing field is large. This leads to stronger linkage between manufacturing field and normal life of people. This may be one reason why so many papers talk about the SSCM in manufacturing perspective. The pure service field contains bank, tourism, hotel, restaurant or retails. According to figure distribution, service has not gained as much consideration as manufacturing does. Though service firms become more and more important to the normal life, limited minds are put on SSCM study here by researchers. However the potential research value of this field is huge, and there will be more and more papers working on service perspective. Here, the logistics field is defined as one embodies pure transportation companies like DHL, TNT and UPS. These kinds of companies only care about the distributing products rather than manufacturing or serving anything else. Because for most of the time, logistic can be discussed in the manufacturing field (distributing product from one place to another or reserve logistic) so that logistic is rarely picked up to study separately. This may be one reason why so few papers located in this field. In this paper, the logistic will be considered as an independent research field and compared with other two fields.
Figure 2.3: Distribution of the papers (number of papers)
Service Logistics Manufacturing 0 10 20 30 40 50 Quantitative
model Case study Survey
Review
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3. Literature Analysis
As mentioned in the introduction phase, three kinds of performance (environmental, social and economic) can be addressed to measure the sustainable supply chain management. Many literatures have a systematic analysis of sustainable supply chain management of these three categories (Series 1 in Appendix 5). Therefore, in this paper the author also decides to look into these three dimensions and integrate them into the article classification. It is hard to study the whole 131 articles at the same time so that the groups are needed for guiding us to the expected findings. The groups are classified by methodologies. Within each group, the articles are distributed into different categories covering three research fields – manufacture, logistics and service; and three kinds of performance measurements – social, environmental and economic. The objective is to compare the sustainable supply chain management performance in different fields and to see whether there are any common and uncommon findings. After the intragroup study, the inter-group comparison will be taken for various methodologies.
3.1 Group 1: Quantitative model
10 Table 3.1 Papers with quantitative model
Related papers in each area
Social Environmental Economic
Manufacturing [20][36][60] [95][120][48] [18] [20][36][43][60][64][70] [79][81][95][96][102] [110][120][48][6][87] [20][36][4][17][18] [32][43][47][60][120] [70][79][81][95][96] [97][98][48][6][87] [122] Logistics [36] [36][25][29][80][109] [110] [36][25][29][80] Service [36] [36][110] [36]
Figure 3.1 Papers with different theories
Within these 28 papers, in (Series 3 in Appendix 5) they have implemented a method called ―Fuzzy set theory‖. ―Fuzzy set theory‖ is described as a tool to translate human factors into numerable value and is very useful in resolving the problems in the decision making process (Lin, 2013). As we known, in a mathematic model every variable cannot be just descriptive but be counted as countable value. However most of human factors
0 5 10 15
Fuzzy set theory Multi-Objective Optimization Model Variational Inequality Model Simulation Model Game Theoretic Model Analytical Hierarchy Process (AHP) theory
Cumulative Energy Demand(CED) theory Others
Papers with quantitative model
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like judgment and preferences are vague, which means they cannot provide exact countable values for the structure of the real model. ―Fuzzy set theory‖ is able to fill this kind of gap. The author takes a further look at (Govindan, Khodaverdi, & Jafarian, 2013) since it covers all three research fields and all three performance measurements. This makes (Govindan et al., 2013) contain more representative than the other two. In (Govindan et al., 2013) the ―Fuzzy set theory‖ is divided into two parts: the fuzzy numbers and fuzzy TOPSIS (Technique for Order Preference by Similarity to Ideal Solution). The fuzzy number is used to evaluate the decision-makers’ performance so that the social performance can be assessed by numerable values. The fuzzy TOPSIS method is applied to combine all the evaluations of three sustainability performance and come up with overall scores. For the economic criteria, some factors such as cost and delivery reliability are selected to be measured. For social criteria, some like health and local communities influence are picked up. For environmental criteria, the pollution production and resource consumption are also assessed by different coefficients. The paper illustrates the theory with four suppliers. The finding indicates that the collaboration of supplier environmental and social in sustainable supply chain management can make a huge contribution to benefits of companies and sustainable development in society. (Wang & Chan, 2013) and (Kannan, Khodaverdi, & Olfat, 2013) combine the fuzzy TOPSIS method and ―Fuzzy set theory‖ to help the managers make a better strategy for sustainable development in all three kinds of performance. (Shen, Olfat, Govindan, Khodaverdi, & Diabat, 2012) supports these findings by applying the same theory in a particular manufacturing area. (Lin, 2013) also shows the importance of taking three kinds of performance into consideration in the meantime when studying on sustainable supply chain practices.
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CED, several preferred solutions for business and environmental factors can be visually identified by decision-makers in the company. This finding indicates that the MOOM can provide managers with the curve of evaluating the trade-offs between benefits and environmental impacts in a certain logistic network. The curve can also lead the managers to explore the optimal solutions. (Frota Neto, Bloemhof-Ruwaard, van Nunen, & van Heck, 2008) proves the results of (Quariguasi Frota Neto et al., 2009) through implementing MOOM again to design a logistic network for a European paper company instead of a Germany company. The MOOM is built to assess the efficiency of the logistic network by balancing the trade-offs between profitability and environmental impacts. (Elhedhli & Merrick, 2012) uses MOOM to find out a significant factor which must be considered when building a logistic network – emission cost - by analyzing the whole cost and environmental impacts of the supply chain. MOOM can also be used in the manufacturing area. In (Series 6 in Appendix 5) they prove that this model is useful to look for optimal solutions for profitability and environmental impacts trade-offs of supply chain network in manufacturing firms. Secondly (Lu, Wu, & Kuo, 2007) and (Tsai & Hung, 2009) are selected to be further focused because they only pay attention to the environmental performance. (Lu et al., 2007) proposes many environmental impact indicators such as energy using and liquid residues. The MOOM is set to support the decision-makers in firms in evaluating the performance of supply chains by considering all the indicators together. Multi-solutions are presented for the decision-makers to choose at the end. (Tsai & Hung, 2009) gives a backup to (Lu et al., 2007) that it uses MOOM to solve the environmental problems in the logistics network instead of manufacturing area. Thirdly (Sheu, Chou, & Hu, 2005) is a unique paper that works only on economic performance. MOOM in (Sheu et al., 2005) takes manufacturing chain-based net profit and reverse chain-chain-based net profit as its variables. The trade-offs between these two variables are shown, and the optimal solutions are offered by MOOM. (D. J. Wu & Kleindorfer, 2005) applies MOOM to addresses the optimal portfolios of business-to-business market transactions in terms of pricing.
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only contribute to economic and environmental performance, but also to social performance. This is an extended implementation of solving equilibrium problems compared to MOOM which only contribute to non-social performance.
Within these 28 papers, 3 papers refer to a theory called ―Cumulative Energy Demand‖ (CED). CED is widely used in measuring the environmental impacts, and it is very easy to understand by researchers. (Series 8 in Appendix 5) are produced based on CED. (Quariguasi Frota Neto et al., 2009) and (Quariguasi Frota Neto, Walther, Bloemhof, van Nunen, & Spengler, 2010) have already discussed in the previous section because they composite the CED and MOOM. (Quariguasi-Frota-Neto & Bloemhof, 2012) continues to pursue the relationship between environmental impacts and the firm’s economic. CED gives the author an opportunity to measure the energy consumption and transfer the assessment into corresponding values. The result shows that remanufacturing is a good way to decrease the energy consumption. This indicates that CED can also be an available tool to study the efficiency of supply chain network regarding the environment and business field. There is another clue that CED is often integrated with MOOM. The MOOM can maximize the benefits of CED when more than one target needs to be achieved. (Savaskan, Shantanu, & Wassenhove, 2004) proves that remanufacturing is important factors in CLSC to enhance the product profitability when dealing with energy consumption by using the method of MOOM. In addition, (Quariguasi Frota Neto, Walther, Bloemhof, van Nunen, & Spengler, 2010) extends the objective of CLSC from optimizing economic profitability of supply chain to reducing environmental issues. The actions of recycling, remanufacturing and reverse logistics are assessed to see whether they are helpful to reduce the environmental problems.
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required to lower the total cost of supply chain if companies go green. There is also evidence that the government involvement is important: (Chen & Sheu, 2009) establishes the GTM and realizes Nash Equilibrium solutions to find the result those rational manufacturers can improve their product recyclability when government increases regulation standards by degrees.
Within these 28 papers, 3 papers refer to a theory called ―Analytical Hierarchy Process‖ (AHP). AHP is a tool to solve the trade-offs in managerial judgment and perceptions so that the decision-makers can collect much information to know what to do. In (Series 10 in Appendix 5) they include this kind of theory. (Lu et al., 2007) and (Tsai & Hung, 2009) synthesize the AHP with the MOOM to create their own quantitative model and are discussed in the preview section. So (Dai & Blackhurst, 2012) is taken as an example to be further analyzed. (Dai & Blackhurst, 2012) aims at consummating the supply assessment by taking more factors (such as the business objective and company stakeholders’ requirement) into consideration. Therefore, not only the economic and environmental performance is measured, but also social performance is added. AHP is integrated with Quality function deployment (QFD) which is a tool for translating the voice of stakeholders into indicators of performance. The AHP-QFD model assists the author to establish a new way to assess the suppliers by four phases. By the model, the understanding of supplier assessment and selection is raised. This indicates that social performance like customer and stakeholders’ requirements need to be thought over when the decisions and judgments are made in SSCM.
Within these 28 papers, 2 papers refer to a theory called ―Simulation‖. Simulation is a technical to run the operations over time. Its purpose is to test or optimize the performance. (Ali & Gupta, 2011) and (Sonesson & Berlin, 2003) implement this method to calculate and measure the supply chain performance. (Ali & Gupta, 2011) talks about the economic performance while (Sonesson & Berlin, 2003) focuses on environmental performance. In (Ali & Gupta, 2011) simulation is used to compute the different costs of the CLSC (disassembly cost, disposal cost, backorder cost) and benefits of the network against different variables (demand rate for component E and product arrival rate). It indicates that simulation is a viable approach to assess the economic performance when the number of variables is large. In (Sonesson & Berlin, 2003) many environmental impacts such as energy consumed and emission is simulated and calculated for further analysis. This indicates that solution model is also available for environmental performance assessment.
As a summary of the quantitative model group, some academic and practical contributions are presented as follows:
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2. MOOM is useful in dealing with the optimization and trade-offs from particular environmental and economic areas;
3. VIM contains the similar function as MOOM, but extends its implementation into social part;
4. CED can play a larger role when it is combined with MOOM;
5. GTM owes similar function as MOOM and is a good approach to integrate the government effects into economic performance of SCCM;
6. AHP has a better contribution when been integrated to MOOM, and it also extends its application range to the social part;
7. Simulation is a better method to calculate the performance when there are too many variables;
8. Social and environmental performance is as important as economic one; 9. There are always tradeoffs between environmental and economic performance; 10. Remanufacturing is a good way to decrease the energy consumption;
11. Government can play a significant role in supporting firms pursuing SCCM; 12. The CLSC mainly deal with the tradeoffs between environmental and economic
performance.
3.2 Group 2: Case study
16 Table 3.2 Papers with case study
Related papers in each area
Social Environmental Economic
Manufacturing [8][11][19][27] [38][51][52][54] [58][66][71][74] [75][84][90] [105][106][117] [118] [123][126] [8][11][12][19][27] [38][39][45][51][52] [54][58][66][67][71] [74][75][78][84][88] [90][101][105][106] [117] [118][123][126] [8][11][19][27][38] [39][45][54][58][66] [71][74][75][78][84] [88][101][105][106] [117] [118][123] Logistics [53] [53] [53] Service [2][35][49][99] [117][118][123] [2][35][28][99][117] [118][123] [2][35][28][99][117] [118][123]
Figure 3.2 Papers with different purposes
In (Series 11 in Appendix 5) they intend to build a new theory or framework through analyzing and discussing cases in practice. Most of these papers only make the study in the manufacturing field.
Within these 8 papers, in (Series 12 in Appendix 5) they mention all the three performance measurements. The paper of (Z. Wu & Pagell, 2011) is taken as an example because it is the only paper covers both manufacturing and service fields. (Z. Wu &
0 5 10 15 20
Theory buidling Theory validation Theory extension
Papers with case study
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Pagell, 2011) aims at finding out an approach for companies to make the right decisions in the supply chain so that both the short-term profitability and long term sustainable development are balanced. All the cases are leader companies with environmental sustainability. A semi-structured interview protocol and interview are developed to collect data from company staffs. Other information is gathered from company websites or annual reports. After the case study, four environmental postures are proposed as a framework to help the decision-makers recognize the opportunities for performance improvement. Another implication of this framework is that managers can use it to evaluate their strategy options and build more sustainable business model. This indicates that the new theory can not only contribute to academic filed by extending its application range, but also contribute to practice through support managers making a better decision in supply chain network. (Azevedo, Carvalho, & Cruz Machado, 2011) is a backup of (Z. Wu & Pagell, 2011) because it also develops a model by a case study to help the manager assess the sustainability performance. An integrative framework is established after studying small and medium-sized suppliers in (S.-Y. Lee & Klassen, 2008), which assists decision-makers in enhance sustainability performance. (Pagell, 2009) supports (Z. Wu & Pagell, 2011) in the way that its new theory can provide managers with a complete understanding of SSCM and lead managers to integrate all the three sustainability performance when designing supply chains.
Within these 8 papers, in (Series 13 in Appendix 5) they devote more attention on social and environmental standards. (Koplin, Seuring, & Mesterharm, 2007) is randomly picked up as an instance because all three papers cover the same range and share similar results. (Koplin et al., 2007) pursues an approach to integrate the social and environmental standards in supply chain management. A single case study of Volkswagen AG is held when the organization has a positive attitude towards sustainability in supply chain management. This case operates as a project so that all the data are collected by monitoring activities in the industry. Then a conceptual framework is developed to implement social and environmental factors into supply chain management. This indicates that the new theory provides the decision-makers with a direction of realizing sustainable development in the supply chain through social and environmental aspects. (Seuring, 2011) also builds a theory with hypotheses for SCCM with social and environmental contents to gain a better understanding of SCCM. (Zhu & Cote, 2004) describes a special theory derived from Guitang Group model to promote operating sustainability including reducing environmental impacts and increasing social responsibility.
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held to get the data. After analysis, a theory of developing a green commodity strategy is proposed with a combination of profit aspect and environmental impacts. The result is that if a manager wants to make a good decision for supply chain strategy, the integration of environmental and economic aspects is necessary. This indicates that the new theory is a good tool to balance the trade-offs between environmental impacts and profitability. In (Series 14 in Appendix 5) each paper owns an existing theory and uses a case study to extend the application range of the theory. Several papers are found in the service fields. Within these 10 papers, 6 papers cover all three performance measurements. In (Series 15 in Appendix 5) they make their contributions in the service field and in (Series 16 in Appendix 5) they point in the manufacturing area. Firstly (Sigala, 2008) is randomly picked up as an example because the three papers study in the same field. In (Sigala, 2008) its purpose is to implement the sustainability concept in tourism supply chain. The existing theory is the SSCM with three performance measurements. A special case of tour operators is visited to measure the adoption of SSCM in the tourism area instead of manufacturing area. After the case study, the model of implementing SSCM into tour operators is identified. The result shows that collaboration of three kinds of performance in the tourism supply chain is difficult to realize but is very important to improve the adoption of SSCM. Some factors like demand pressures and forces can motivate the implementation of SSCM. But some may decrease the motivation, for example the lack of cost saving benefits. It indicates that a regulatory framework is needed to guide tour operators integrate the suitability into the supply chain in consideration of all the good or bad drivers. (Adriana, 2009) proves this indication by examining 8 tourism operators. (Gopalakrishnan, Yusuf, Musa, Abubakar, & Ambursa, 2012) investigates a security service company and develops a more mature framework for interdependency of three kinds of performance. It contributes to some useful drivers for applying SSCM in a service supply chain. (Font, Tapper, Schwartz, & Kornilaki, 2008) also provides some drivers of SSCM improvement on environmental and economic areas when making the SSCM widely used in tourism. (Keating, Quazi, Kriz, & Coltman, 2008) pursues a suitable supply chain in the service field by observing the social performance in a bank service firm. A practical model is built based on corporate social responsibility theory to guide the service firms achieving sustainability in their supply chains.
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build the sustainable strategies for firms. It indicates that SSCM has included many aspects (production, purchasing, transportation, etc.) and the potential extensions of SSCM application into various aspects with different paths are available. (Curkovic & Sroufe, 2011) presents an ISO 14001 method to promote the SSCM strategy. All three kinds of performance are measured in ISO 14001 so that this method is helpful for managers identify the dimensions of sustainable supply chain. (Reuter, Foerstl, & Blome, 2010) proposes a sustainable global supplier management regarding SSCM to enhance the competitive advantage in sourcing accumulation from a worldwide perspective. (Caniato, Caridi, Crippa, & Moretto, 2012) supports (Pagell et al., 2010) and (Pagell et al., 2010) by implementing SSCM in fashion companies, especially environmental indicators of measuring SSCM are listed for better pursuing sustainability objective. (Mintcheva, 2005) also supports (Pagell et al., 2010) by applying SSCM in food industries. A group of environmental indicators is also proposed to address environmental issues in the food supply chain.
In (Series 17 in Appendix 5) each paper describes a theory or framework at the beginning and then tests the theory by applying cases.
Within these 16 papers, 11 papers contain all three kinds of performance. (Walker, Di Sisto, & McBain, 2008) and (Walker & Jones, 2012) mention both manufacturing and service areas. In (Series 18 in Appendix 5) they only talk about the manufacturing field while (Kudla & Klaas-Wissing, 2012) only refers to logistics field. Firstly (Walker et al., 2008) is chosen as an illustration since it makes an effort in two research fields. The objective of (Walker et al., 2008) is to detect the drivers of implementing SCCM. Seven manufacturing and service firms are interviewed to collect the data. The case study is built to test some existing indicators of three kinds of performance and to distinguish some new indicators. The result tells that not only drivers to SSCM practices exist, but also barriers appear. And the drivers are more than barriers. It indicates that the SSCM application in industries is encouraged and profitable. (Walker & Jones, 2012) proves this indication that the organization is motivated to support SSCM by examining other several cases particularly in the UK.
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Thirdly, the paper of (Cabral et al., 2012) is to be discussed since it is a representative of papers in the manufacturing area. (Cabral et al., 2012) is tending to transfer the SSCM theory into practices and develop key performance indicators to measure the influence. An analytic network process model is proposed to help the decision-makers choose the best practices. A manufacturing company is selected as a case to demonstrate the implementation of the model. The result tells that this model is flexible for managers to make decisions related to SSCM because it combines all three performance measurements with all kinds of indicators. This makes decision-makers easier to evaluate the performance in SSCM and find the most appropriate practices. It indicates that building a comprehensive model which integrates all three performance indicators can make a big difference for decision-makers to select the best SSCM practices. In (Series 19 in Appendix 5) they demonstrate this implication separately by designing their own three performance measurements models and applying them to assess and improve the SSCM practices in different companies. (Foerstl, Reuter, Hartmann, & Blome, 2010) and (Hall & Matos, 2010) contribute to this indication by realizing the importance of considering interactions among three kinds of performance in sourcing practices of SSCM.
Within these 16 papers, 4 papers refer to environmental and economic performance in the manufacturing area. In (Series 20 in Appendix 5) they share a common element called environmental information. The aim of (Solér, 2010) is to recognize the significance of environmental information in SSCM to make companies more competitive. A Swedish food supply chain is investigated to test the relationship between performance of supply chain and information sharing. The result shows that environmental information is an important element to develop the SSCM theory. It indicates that conducting environmental information is a good way to improve the sustainability performance in the supply chain. (Jabbour & Jabbour, 2009) enhances the importance of environmental information by comparing 4 companies without information database and 1 company with information database. (Preuss, 2005) makes a contribution that management of information is one of the vital elements to push firms green in terms of supply chain network. (Schiefer, 2002) also concludes that a suitable information flow initialization plays a role in addressing environmental problems in the supply chain.
As a summary of the case study group, some academic and practical contributions are presented in following:
1. A new theory or framework derived from SSCM contributes to both scientific research and practices;
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3. Integration of environmental and economic performance and balancing trade-offs between them can benefit companies;
4. Good drivers of SSCM can motivate managers to implement sustainability in supply chain while poor ones decrease initiative;
5. SSCM exists along the entire supply chain from purchasing material to distributing goods. Extending SSCM into some particular areas can enrich the framework of SSCM;
6. It is worth applying SSCM since it enjoys more drivers than barrier;
7. Taxonomy is developed for people researching purchasing sustainability in the logistics area;
8. Consideration of all three kinds of performance can enhance the comprehensive model of SSCM. And it makes managers easier to find the best solution of implementing SSCM;
9. Environmental performance investigation can also promote SSCM theory. 3.3 Group 3: Survey
22 Table 3.3 Papers with survey
Related papers in each area
Social Environmental Economic
Manufacturing [3][10][42][46] [50][56][62][65] [72][76][108][111] [112][113][115] [125][121][69] [127] [3][10][21][22][26][30][37] [42][46][50][55][56][57][62] [65][72][76][82][83][94] [100][107][108][114][111] [112][116][113][115][124] [125][129][130][131][132] [134][136][133] [135][121] [69][127] [3][10][21][22][26] [42][46][50][56][65] [72][76][82][83][94] [107][108][114][112] [116][115][124][125] [129][130][131][132] [134][136][133][135] [121][69][127] Logistics [3][62] [3][62][94] [3][94] Service [3][42][62][115] [121] [3][42][57][62][94] [115][121] [3][42][94][115][121]
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performance criteria. The effect of SSCM practices on three kinds of performance from a manufacturing view is found that environmental cooperation benefits the performance. In (Series 22 in Appendix 5) they pay their attention to the dimension of green supply chain management. They recognize that implementation of green supply chain management brings profitability to companies from three kinds of performance viewpoints. (Mathiyazhagan, Govindan, NoorulHaq, & Geng, 2013) points out the barriers to application of green supply chain management in Indian industries. (Paulraj, 2011) conducts the dimension of managerial approaches for SSCM and finds that individual purchasing strategy cannot contribute to firm’s sustainability. (Thun & Müller, 2010) investigates the barriers and performance criteria in green supply chain. In (Stephan Vachon & Klassen, 2006a) the relationship between suppliers’ cooperation and performance indicators is built. (Stephan Vachon & Mao, 2008) explores the supply chain characteristics through measuring three kinds of performance and shows that supply chain has a positive connection with these three sustainable decisions. (Zailani, Jeyaraman, Vengadasan, & Premkumar, 2012) works on sustainable purchasing and package to describe the benefits of implementing SSCM in manufacturing industries. (Wong, 2013) considers environmental information integration as a managerial approach to improve the firm’s environmental adaptability. (Muduli, Govindan, Barve, & Yong, 2012) identifies the barriers of SSCM practices.
Within these 42 papers, in (Series 23 in Appendix 5) they incorporate environmental factor with social factor. (Liu, Yang, & Qu, 2012) is taken out for mainly discussion because all three research areas are included. In (Liu et al., 2012) the SSCM practice level is measured. A questionnaire survey is carried out in 165 companies to extend the determinant factors of SSCM from internal variables to external variables. The result shows that the clients’ pressure is one of key external factors to influence implementation of SSCM. It indicates that not only cooperating with suppliers, but with customers will impact the level of SSCM practice in companies. (Stephan Vachon, 2007) and (Stephan Vachon & Klassen, 2006b) highlight the importance of integration with customers when technologies are used to improve the SSCM practice.
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cooperative supply chain sustainable management. In (Series 24 in Appendix 5) they complement SSCM with environmental management system to enhance the view that improving the sustainability requires not only within organizational boundaries, but also across the whole supply chain network. (De Giovanni & Esposito Vinzi, 2012) and (Eltayeb, Zailani, & Ramayah, 2011) provide a prerequisite which is an internal environmental management (such as green raw material ) to achieve better collaboration outside firms. (Rao & Holt, 2005) puts evidence that improving environmental performance by reducing energy usage can lead to competitive in economic performance. (S. Vachon & Klassen, 2007) reinforces the integration and cooperation between suppliers and customers to benefit environmental and economic performance in firms. (Youn, Yang, Hong, & Park, 2011) proves that mature trust is a significant antecedent for SSCM practice and a base for collaboration among supply partner.
Secondly (Zhu & Sarkis, 2004) is chosen specially since it contributes to a set of questions related to SSCM practices and environmental, economic performance measurements. The purpose of this article is to determine the relationship between SSCM performance and practices. A survey is conducted in Chinese manufacturing organizations. One rotated factor matrix for SSCM practices and one for performance influences are proposed to gather the data. The result shows the relationship by calculating the correlations between performance and practice. It indicates that these two rotated factor matrixes can be widely used to solve problems in terms of SSCM practices and performance. (Zhu & Sarkis, 2006) combines the practices factors and new developed drivers of SSCM to measure the drivers and practices of SSCM in Chinese companies. In (Series 25 in Appendix 5) they add and examine an institutional pressure factor in the relationship between SSCM practices and performance. (Zhu, Sarkis, & Lai, 2008a) and (Zhu, Sarkis, & Lai, 2008b) develop a confirmatory factor analysis based on the theory of (Zhu & Sarkis, 2004) and testify the implementation of SSCM. (Zhu, Sarkis, & Lai, 2012) uses the same matrixes mentioned in (Zhu & Sarkis, 2004) to evaluate the internal and external effect of SSCM practices on performance improvements.
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to satisfy customers’ environmental requirements. (Hajmohammad et al., 2013) puts its effort in explaining the role between lean management and environmental practice. It presents that resource can be allocated more effectively to improve the environmental performance with the help of lean. (Large & Gimenez Thomsen, 2011) underlines collaboration among suppliers as an influence factor on environmental performance because more resource from whole supply chain networks can be integrated for sustainable developments.
As a summary of the survey group, some academic and practical contributions are presented in following:
1. A basic framework for SSCM along 7 dimensions is tested: reasons for SSCM; green supply chain; characteristics of suppliers; benefits and motivations of SSCM; managerial approaches for SSCM, barriers for SSCM, and performance criteria for SSCM;
2. Collaboration with suppliers and customers is important to enhance implementation of SSCM;
3. Integration of environmental and economic performance is highlighted;
4. Trust can encourage cooperation in the supply chain level and the increase SSCM initiative of firms;
5. Two basic rotated factor matrixes are built to measure SSCM practices and performance (environmental and economic);
6. Environmental practice can produce the best possible results with other supports such as investments, top management commitment or lean practice.
3.4 Group 4: Review
26 Figure 3.4 Papers with literature review
Firstly (Carter & Rogers, 2008) is selected. In (Carter & Rogers, 2008) the topic is building a framework of SSCM and discovers the relationship among three sustainability performance. This article recommends the concept of sustainability through integrating three kinds of performance criteria to make firms profitable. A new conceptual model is built for extending the concept of sustainability beyond three kinds of performance criteria to recognize the prerequisites for implementing SSCM practices. Some propositions for SSCM are developed according to the resource, cost and population ecology and needs to be tested in future research. In (Series 27 in Appendix 5) they also work on developing the framework of SSCM. In (Carter & Easton, 2011) SSCM is seen as a basic theoretical framework for moving to the other theory and methodology in future research. In (Chakraborty, 2010) SSCM can be seen as a complement to the increasing environmental consideration and ecological footprint involving SCM. In (Hassini, Surti, & Searcy, 2012) the framework including factors of supply chain partners and three performance measurements is developed after literature review. (Carter & Easton, 2011) and (Hassini et al., 2012) try to find the connection among three sustainability performance. Some performance indicators are proposed after study.
In (Linton, Klassen, & Jayaraman, 2007) the topic is sustainable development in the entire supply chain level. Both the natural and social sciences are identified to pursue sustainability through policy changing. The government policy and production operations can be influenced by sustainable development. Some new business models may be created in the academic research. The entire production system needs to be considered when developing sustainability in terms of supply chain management. (Gimenez & Tachizawa, 2012) supports (Linton et al., 2007) by figuring out the impact of governance
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policies on implementing sustainability to suppliers. Environmental and social performance is positively influenced by supplier assessment and collaborative practices. In (Sarkis et al., 2011) the topic is to investigate the adoption, dissemination and consequence of SSCM according to several organizational theories. 9 organizational theories related to SSCM are identified, and 4 future organizational theories for SSCM are proposed. The organizational theory is useful for inspecting research in SSCM. There are also opportunities for further research with applied theories and even new theories. The method to link the organizational theories and SSCM practices are still lacking. In (Dües, Tan, & Lim, 2013), it provides a method to integrate lean theory and SSCM practices. An overlap of lean and SSCM is identified in several aspects such as waste reduction, lead time reduction, supply chain relations and KPI. Lean theory can be seen as a driver to motivate SSCM practices. Integration of lean and SSCM will increase companies’ profitability.
In (Seuring & Müller, 2008a) the topic to take an overview of papers in the field of SSCM and to develop a conceptual framework for explaining the triggers of SSCM, supplier risks and performance and sustainable products in supply chain management. Three distinctive features of SSCM are provided: 1) SSCM needs to be seen from a long-term perspective; 2) environmental and social performance of sustainability need to be considered; 3) need for cooperation among suppliers in SSCM practices. The future research direction may be extending the framework from a research methodology viewpoint. (Seuring et al., 2008) discusses environmental and social problems throughout the entire supply chain by taking a closer look at regional activities in small and medium-sized manufacturing companies. The result shows that papers talking about the social aspect cannot be found as much as ones with environmental issues. (Ashby, Leat, & Hudson-Smith, 2012) researches the social and environmental dimensions in SSCM which align two concepts of sustainability and supply chain management. Social dimension like communication gets much less emphasis than environmental factor. And the integration between these two dimensions seems to be limited in SSCM. (Hoejmose & Adrien-Kirby, 2012) also presents a framework including the effects of the external environment and internal sociality on responsible procurement process in the supply chain.
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improvements of planning and control for equipment decision, inventory and transportation in the supply chain is presented.
There are in total 14 review papers being distributed from 2007 to 2013. For each year, some topics are popular, and others are neglected. Figure 3.5 shows the tendency of changing research topics in SSCM. The detailed academic or practical contributions of each paper will be compared with the ones from preview groups (quantitative model, case study and survey) in the discussion section.
Figure 3.5 Research topics
2006 2007 2008 2009 2010 2011 2012 2013 2014
Topic
Sustainable development Framework of SSCM
Three sustainability performance Triggers and initiative of SSCM Integration of environmental and social Economic performance
Environmental performance
Operations Research in sustainable logistics Assessment & collaboration
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4. Discussion and future directions
The academic contributors from other papers and practical contributions in real-world organizations are organized and showed in the previous section. They are also clearly listed in Appendix 3. The objective of identifying contributions from other scholars is realized. Then the author intends to reach another objective: propose future research for other researchers. It will be achieved by discussing results derived from each group, comparing the contributions among four groups and discovering the gaps. In the first four sections, future research directions are proposed based on analyzing the results within each group. In the fifth section, future research is put forward based on cross-group comparisons. In the sixth section, this paper is compared with other literature reviews. In the last section, several papers that are wiped out due to four methodologies settings but highly cited in publics are selected to see whether any future directions can be identified. 4.1 Quantitative model
Quantitative modeling can be seen as a tool to apply SSCM theory into practices. In the economic aspect, the model can be used to calculate the revenue and cost of firms or supply chain. In the environmental section, the model can quantify the environmental impact such as waste emission, waste reduction or landfill. In the social aspect, the model can transfer human resources into countable values. Managers can adjust strategies and choose the best solution for operations by comparing and optimizing results of the model. Less social problems are addressed than environmental and economic ones. This may be due to the fact that only ―Fuzzy set theory‖ and AHP theory can quantify social problems. More quantitative methods are needed to enhance SSCM research weight on social performance measurement. Figure 3.1 shows that MOOM is widely used to deal with the trade-offs between environmental and economic performance in SSCM. But its application range is narrow. It may solve the social issues only when it is combined with AHP. In the future the combination of MOOM and ―Fuzzy set theory‖ can be built. There is a phenomenon that many papers in this group prefer combining two different methods to extend their research range. But a systematic guideline that can help other scholars choose a suitable combination of methods is missing. In the future, it is encouraged to build this kind of guideline. Table 3.1 clearly reminds us that very few quantitative models are implemented in the service field, probably due to little research interest in this area. Today with increasing demands of service like banks, tourism or retailers, more academic and practical research in the service field is desired.
The discussion within this group leads to a research proposition:
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4.2 Case study
Case study is applied for three approaches: building new theory; extending existing theory to a new application range; testifying and validating existing theory. From Figure 3.2, the author can see that nearly 50 percentages of case study papers are for theory validation. It indicates that in current years, research in SSCM becomes much mature than 10 years ago. Many theories can be applied directly into industry practices. However, all the papers with new built theories only talk about manufacturing area and have not made the connection between social and economic performance. Future research can locate in creating more theories for logistics and service fields. New theories of mapping relationship between social and economic performance are called. From Table 3.2, it is obvious that only one paper puts its effort in logistics field. This is puzzling because transportation process is one of the most important elements in supply chain management. The impact of sustainable development in this area should be investigated in future research.
The discussion within this group leads to a research proposition:
P2: More research efforts are put into integration of environmental and social, environmental and economic performance rather than the relationship between social and economic performance. Few case studies are carried in logistics and service fields. 4.3 Survey
The survey is an effective tool to check hypotheses produced by researchers. From Table 3.3, a tendency is identified: most of the articles test their theories for environmental and economic performance in the manufacturing area. In future research by surveys, the range of application of SSCM is expected to expend to both social performance and service, logistic fields. The integration of social and economic performance is blank so that a future direction is recognized. The single performance analysis (only study in one kind of performance) happens to the environmental aspect. Table 3.3 shows that survey research never goes into social or economic perspective solely. This discovers a potential way for the survey study in SSCM. There is a phenomenon that all survey papers investigate the manufacturing field. But few papers study the logistics or service field specially without mentioning the manufacturing field. The contribution of each paper becomes less specific and harder to be distinguished in the view of research fields. Future research needs to specialize on three research fields separately in order to highlight characteristic of contributions from various fields.
The discussion within this group leads to a research proposition:
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4.4 Review
In previous reviews, the framework of SSCM has been built according to three performance measurements. In this paper, three kinds of performance are investigated in three research fields. Therefore, an overview of how SSCM performs in different research areas is presented. However the detailed performance indicators are still missing. Future research can study three performance indicators in three research fields. In previous reviews, SSCM is commented from a research methodology viewpoint. Here in this paper, SSCM is investigated under the categories of both quantitative and qualitative methodologies. In each methodology, SSCM performance is fully measured. The categories of methodologies can be reconsidered (for example, add simulation as a new methodology when classify the papers) in the future because only four methodologies are identified in these papers.
The discussion within this group leads to a research proposition:
P4: The three performance measurements concept is introduced by recent literature review, but the performance indicators need to be comprehensively summarized.
4.5 Cross-Groups comparison
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methodology, a concept of remanufacturing is proposed to decrease the environmental impacts on the supply chain. But this is not taken seriously in the other two methodologies. Future research can use case studies and surveys to illustrate remanufacturing practice. In survey methodology, collaboration with suppliers and customers influences the implementation of SSCM positively. In future research, some mathematical methods can be developed to value the relationship between collaboration and SSCM practices. The tradeoffs between environmental and economic performance in CLSC are always solved by quantitative models, especially by MOOM. In future research, more other methodologies (case study or survey) can be attempted to deal with these tradeoffs.
The discussion within this group leads to following research propositions:
P5: SSCM research in current years appears frequently in manufacture field. The logistics area gets even less attention than service area.
P6: Tradeoffs between environmental and economic becomes a popular goal for companies when implementing the SSCM.
P7: Cooperation and government support among supply chain play key roles of SSCM practices.
P8: Remanufacturing helps develop sustainability in supply chain.
P9: CLSC can help improve two kinds of performance (environmental and economic) in SSCM.
4.6 Comparison with other literature reviews
This paper aims at evaluating all three kinds of sustainability performance in three research fields by reviewing all kinds of papers with different research methodologies. Other literature reviews put more effect on a specific area – environmental and social performance evaluation. They come up with a statement that there is a positive effect of collaborative practice among the supply chain on environmental and social performance. Several survey papers reviewed by this paper also come up with this statement. But the papers with quantitative model and case study methodologies have not proven it yet. In the future, other methodologies such as quantitative model or case study are strongly recommended checking this statement again.
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industry practice. This can be seen as a complement to the previous reviews work. However, there are total 9 organization theories provided by previous works so that future research can aim at linking all these theories to practice.
In previous papers, the environmental and economic performance is frequently investigated. Some papers have found the effect of environmental performance on sustainability and others emphasize economic performance impact. This paper also recognizes these contributions by reviewing case study and survey papers. However this paper indicates that the importance of detecting social performance in SSCM has not been recognized yet. This provides a direction for future research.
4.7 Other typical articles
As mentioned before, there are initially 131 papers about SSCM. Some of them that do not use any of above four methodologies to solve the problems are wiped out for further analysis. Within the 20 removed articles, (Hutchins & Sutherland, 2008) is cited by 121 times; (Sarkis, 2003) is cited by 522 times; (Seuring & Müller, 2008b) is cited by 91 times and (Svensson, 2007) is cited by 102 times. They are cited by other scholars for a high number of times. The author decides to take special treatments on these four papers. In (Hutchins & Sutherland, 2008) a strategy including social sustainability measures is offered with identification of corporate social responsibility (CSR) indicators. This is a social performance study. It points a way for future research that CSR can be combined with SSCM to investigate social performance. (Sarkis, 2003) develops a decision framework for SSCM based on an environmental practice. This may be another potential way that perfecting frameworks of SSCM can be achieved by not only reviewing past articles, but also being inspired from practices. (Seuring & Müller, 2008b) solves some core issues in SSCM by a method called ―Delphi study‖ which is useful for the empirical research. Structuring group communication and accessing group opinion make ―Delphi study‖ a good tool to evaluate the comprehension of SSCM. ―Delphi study‖ may become a new widely used method to deal with sustainable problems in supply chain management. More future work can be done by this method. In (Svensson, 2007) a first-, second- and n-order supply chains concept is presented to explore firms’ efforts of SSCM. Future research needs to pay more attention to n-order supply chain rather than first-order supply chains when solving sustainable issues.
5. Conclusion
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missing academic and practice contributions have been proposed together with recommended research proposals which lead to future research. Both two research questions are answered during the discussion. Scientific and practice contributions from papers using different methodologies are not identical. There are some common or similar results from various methodologies while others are diverse. The contributions listed at the end of each group in Section 3 provide evidence for this statement. The contributions from papers in different research fields are also not identical. This has been proven with the detailed analysis in each group in section 3. Based on the discussion provided by this paper the other scholars can know what further research to be engaged. Next, the research and practical implications are discussed.
5.1 Research implications
The academic contribution of this paper is taking an overview of research results in terms of SSCM in last 10 years and summarizes the contribution in a clear list. This provides other scholars who want to study SSCM topic with a guideline. This guideline can help locate relevant papers to particular areas. For example, if a scholar wants to write a paper which studies social performance of SSCM by using a survey, he can firstly look into Table 3.3 to see related papers in the same area and check Appendix 3 to know what has been done in this area. This will benefit for scholars to build their own research directions. The future research recommendations of this paper are also a key academic contribution to help expend the research in SSCM. After the discussion, the author can see that case study or survey methodologies are used to figure out the indicators of three kinds of performance. A potential literature review that summaries all kinds of indicators by the case study or survey papers can enhance the framework of SSCM (P4). The mathematical methods can also be applied to measure the indicators and see the weight of effects of different indicators’ on companies. Therefore, the indicators with a remarkable impact on companies can be focused on researching by other scholars.
To enhance the comprehensiveness of SSCM research, some complements can be made based on the propositions (P1 - P6).
