This research considers a real-world GSS problem in Indian automobile industry to show the aptness of the proposed research framework. The Indian automobile industry is a prime driver of macroeconomic growth and technological advancement. India is expected to emerge as the world’s third-largest automobile market in terms of volume by 2026 [96]. In the financial year 2020-21, the total production of vehicles including passenger vehicles, commercial vehicles, three-wheelers, and four-wheelers in India was around 22.70 million units. The Indian automotive industry is expected to reach US$ 300 billion by 2026. The Indian automobile industry turnover encompasses 7.1% of national GDP, 49% of total manufacturing output and provides about 37 million direct and indirect employments [97]. This radical expansion of the Indian automobile industry has put a lot of burden on the environment because vehicle is the core of the automobile industry and they alone can produce 80% of the entire life cycle pollution [2]. Thus, it is the high time for Indian automobile manufacturing organizations to make their supply chain greener with the help of GSS.
The GSS problem formulated in this study considers three India-based automobile manufacturing organizations based on their environmental awareness (ISO 9001, ISO 14001). Initially ten automobile manufacturing organizations were considered but only three organizations shared their enthusiasms for this research. It is worth mentioning that the number of case organizations is not a major issue here. In other words, as the GSS process is carried out using MCDM methods, any number of organizations can be considered for evaluation. In practice, these organizations are striving to attain sustainability in their business by taking several green initiatives, such as, utilizing renewable sources, recycling scrap and wastes, installing emission control devices, using eco-friendly materials, and waste water treatment. The names, locations, and other details of the organizations are kept anonymous in this study due to the privacy policy. Hence, they are termed as ‘Supplier 1’, ‘Supplier 2’, and ‘Supplier C3’ respectively. The brief business profile of the selected organizations is shown in Table 2.
Table 2
Business characteristics of organizations
Suppliers | Turnover (US $- billion) | Type of vehicles produced | Number of associate suppliers | Total number of plants across the country | Number of workers | Total vehicles produced/ year (million) |
Supplier 1 | 26 | Two wheelers, CNG Auto | 675 | 6 | 44,330 | 10 |
Supplier 2 | 32 | Commercial vehicles, Trucks | 1270 | 4 | 14,980 | 5.4 |
Supplier 3 | 40 | Heavy duty vehicle, Passenger bus | 2150 | 9 | 65,780 | 7.6 |
The stepwise application of the proposed research framework is discussed below:
Step-1
In this step, essential evaluation criteria of GSS are determined. An extensive literature review is carried out to identify the most important and relevant criteria. A precise GSS process will occur only if an appropriate set of relevant evaluation criteria are identified, verified, and adopted. This is justified because different organizations have distinct supply chain characteristics and the selected criteria must comply with the supply chain characteristics of the case organizations. In order to do so, the rough list of GSS process was discussed with the experts in this domain through some random meetings. The preliminary list of GSS criteria was validated using different decision measures. Referring to the meetings, the experts examined these criteria with their experience in real-time SS process. Although the primary list of evaluation criteria is prepared from the existing literature, the final list is enriched with the experience of experts for solving real-world problems more feasibly. In this research, fourteen important GSCM criteria are extracted from the extant literature and verified by the experts for final evaluation. As discussed earlier, this research intends to incorporate Environmental, economic, and operational criteria into the GSS process, which are enlisted in Table 3.
Table 3
Criteria | Notation | Dimension | Source |
Increase in investment for GSCM | P1 | Economic | Hendiani et al. [14] |
Savings in total cost | P2 | Economic | Memari et al. [52] |
Effective waste management system | P3 | Environmental | Jain et al. [29] |
Use of emission control systems | P4 | Environmental | Hussain et al. [40] |
Use of energy-efficient technologies | P5 | Operational | Guarnieri et al. [36] |
Reuse of material | P6 | Operational | Yazdani et al. [63] |
Reduction of scrap materials | P7 | Operational | Gupta et al. [2] |
Collaboration with suppliers for green purchasing | P8 | Environmental | Li et al. [78] |
Environmental planning | P9 | Environmental | Pourjavad et al. [43] |
Application of robust environment policy | P10 | Environmental | Ray et al. [28] |
Generation of hazardous wastes | P11 | Environmental | Aslani et al. [37] |
Use of eco-friendly packaging material | P12 | Environmental | Weber et al. [47] |
Top management commitment for GSCM implementation | P13 | Environmental | Sahoo et al. [10] |
Design for proper utilization of resources | P14 | Operational | Ghosh et al. [11] |
Thereafter, a structured questionnaire [28] is prepared to capture a specific set of queries regarding the GSS problem. It comprises of three parts namely, the general part, the technical part, and the miscellaneous part. The general part contains questions about the basic information, such as the nature of the business, total number of employees, turnover, and so on. The technical part includes queries about different GSCM activities carried out by the organizations and their performance measures. The last part deals with miscellaneous information, such as various constraints and GSCM strategies.
Step-2
After selection of case organizations, detail information regarding research objectives are sent to the corresponding industry officials. An expert committee is constituted, which consists of 20 members from each organization (a total of 60 members), among which 5 members from the strategic level, 5 members from the tactical and 10 members from the operational level are selected. The selected members are highly skilled in their respective domains and they have more than 20 years of corporate expertise related to supply chain operations. Communications with the industry experts are established through e-mails, telephone calls, and frequent site visits. Then, interviews with the experts are carried out separately and individual responses are collected very carefully to avoid any kind of possible personal as well as professional bias. During the interview process, the questionnaire is distributed among the experts, who, individually assign their preference ratings in view of the importance of criteria and also provided their opinion. Experts’ ratings are measured using a 9-point linguistic scale [17], where a rating of 1 means the corresponding criteria is less significant and 9 means extremely significant. Since the data is gathered from 20 individual responses of the experts from each organization; therefore, the mean value of those responses is considered for a single criterion [28]. After carrying out the interviews, individual responses are compiled together, and finally a data matrix with criterion value for each alternative is constructed. The data matrix is formed after sorting the raw data according to the requirements without any kind of manipulation, and shown in Table 4.
Table 4
Suppliers | P1 | P2 | P3 | P4 | P5 | P6 | P7 | P8 | P9 | P10 | P11 | P12 | P13 | P14 |
Supplier 1 | 8 | 6 | 9 | 6 | 7 | 8 | 7 | 7 | 8 | 7 | 5 | 7 | 6 | 6 |
Supplier 2 | 7 | 5 | 7 | 5 | 4 | 6 | 8 | 5 | 7 | 6 | 6 | 8 | 3 | 4 |
Supplier 3 | 7 | 8 | 7 | 6 | 8 | 7 | 7 | 8 | 8 | 6 | 8 | 7 | 5 | 7 |
Step-3
The data analysis is performed using TIBCO STATISTICA software. First, the item analysis is carried out to check the consistency of the data. The Cronbach’s value is obtained using Eq. (1). In this analysis, the value is found to be 0.8519, which is sufficiently high and meets the consistency criterion of item analysis. It also implies that the items (criteria) are highly correlated with each other and the dataset is consistent and reliable for making any strong decision. Table 5 shows the omitted item statistics, which represents the modified values after omitting the corresponding items from the dataset. It is used to determine whether eliminating an item from the dataset or adding an extra item to the dataset improves the consistency or not. From the table, it can be seen that the value has not changed significantly after omitting each item from the dataset. For example, if the first item or criteria (P1) is eliminated, the modified value becomes 0.8504, which is very much close to the original i.e., 0.8519. Similarly, it can be been seen for the remaining items also. Therefore, the dataset is reliable and the criteria are highly correlated with each other. However, there is no need to add or eliminate any item (criteria) from the dataset as the omitted item statistics suggests that they all measure the same characteristics.
Table 5
Omitted item | P1 | P2 | P3 | P4 | P5 | P6 | P7 |
Modified alpha value | 0.8504 | 0.8233 | 0.8529 | 0.8324 | 0.7992 | 0.8289 | 0.8846 |
Omitted item | P8 | P9 | P10 | P11 | P12 | P13 | P14 |
Modified alpha value | 0.8061 | 0.8324 | 0.8504 | 0.8690 | 0.8846 | 0.8137 | 0.8061 |
After the aforesaid analysis the well-known PCA method is applied. The number of PCs is equal to the number of criteria considered in this study (i.e., 14). Therefore, the number of PCs to be considered is determined by the magnitude of the eigenvalues. Table 6 shows the PCs and their corresponding eigenvalues. Table 6 highlights only five PCs out of 14. According to the theory, PCs with the highest eigenvalues (greater than 0) should be retained. The first PC has an eigenvalue of 9.7751, the second PC has an eigenvalue of 4.2249, and the remaining items have zero eigenvalues.
Table 6
Principal components | PC1 | PC2 | PC3 | PC4 | PC5 |
Eigenvalue | 9.7751 | 4.2249 | 0.0000 | 0.0000 | 0.0000 |
Cumulative proportion | 0.698 | 0.302 | 0.000 | 0.000 | 0.000 |
The cumulative proportion is used to estimate the amount of variance explained by the PCs. Table 6 shows that PC1 and PC2 together explain the entire variation in the dataset (\(69.8+30.2=100\%\)). Therefore, except PC1 and PC2, the remaining PCs have no contribution to the variation. Since PCA is employed here to determine the criterion weight, the threshold value for the cumulative proportion is set to 0.60 [28]. According to Table 6, the proportion of PC1 is 0.698, which is greater than the threshold value. Therefore, only PC1 is considered to determine the weight. Thereafter, final weight is computed by squaring the eigenvalues of the criteria corresponding to PC1. The weight matrix is shown in Table 7, which indicates P8 secure the highest weight (i.e., 0.564).
Table 7
Criteria weights obtained by PCA
Criteria | P1 | P2 | P3 | P4 | P5 | P6 | P7 |
Weight (\({\text{w}}_{\text{j}}\)) | 0.024 | 0.021 | 0.045 | 0.096 | 0.032 | 0.010 | 0.001 |
Criteria | P8 | P9 | P10 | P11 | P12 | P13 | P14 |
Weight (\({\text{w}}_{\text{j}}\)) | 0.564 | 0.101 | 0.020 | 0.028 | 0.024 | 0.014 | 0.208 |
The ranking of the criteria based on their PCA weight is as \(P8>P14>P9>P4>P3>P5>P11>P12=P1>P2>P10>P13>P6>P7\). P8 gains the highest weight. Hence, ‘collaboration with suppliers for green purchasing’ is the most influential criteria for green supplier evaluation. On the contrary, P7 has the least weight. Hence, ‘reduction of scrap material’ has no significant contribution to GSS. Additionally, from Table 7, it can be said that P14 or ‘design for proper utilization of resources’, and P9 or ‘environmental planning’ are important GSCM criteria as they have relatively higher weight than other criteria.
Lastly, the SAW method is helps to calculate the performance score of the suppliers and rank them accordingly. The data matrix (Table 4) is normalized using Eqs. (3) and (4). The normalized data matrix (\(\text{R}\)) is shown in Table 8.
Table 8
The normalized data matrix (\(\text{R}\))
Suppliers | P1 | P2 | P3 | P4 | P5 | P6 | P7 | P8 | P9 | P10 | P11 | P12 | P13 | P14 |
Supplier 1 | 0.87 | 0.75 | 1.00 | 1.00 | 0.87 | 1.00 | 0.87 | 0.87 | 1.00 | 1.00 | 1.00 | 0.87 | 1.00 | 0.86 |
Supplier 2 | 1.00 | 0.62 | 0.78 | 0.83 | 0.50 | 0.75 | 1.00 | 0.62 | 0.87 | 0.86 | 0.83 | 1.00 | 0.50 | 0.57 |
Supplier 3 | 1.00 | 1.00 | 0.78 | 1.00 | 1.00 | 0.87 | 0.87 | 1.00 | 1.00 | 0.86 | 0.62 | 0.87 | 0.83 | 1.00 |
Thereafter, the weight (ref. Table 7) is multiplied with the normalized data (ref. Table 8) in order to obtain the weighted normalized data matrix (\(\text{C}\)) depicted in Table 9.
Table 9
The weighted normalized data matrix (\(\text{C}\))
Supplier | P1 | P2 | P3 | P4 | P5 | P6 | P7 | P8 | P9 | P10 | P11 | P12 | P13 | P14 |
Supplier 1 | 0.021 | 0.016 | 0.045 | 0.004 | 0.028 | 0.010 | 0.001 | 0.494 | 0.001 | 0.020 | 0.029 | 0.022 | 0.015 | 0.179 |
Supplier 2 | 0.024 | 0.014 | 0.035 | 0.003 | 0.016 | 0.007 | 0.001 | 0.353 | 0.001 | 0.018 | 0.024 | 0.025 | 0.007 | 0.119 |
Supplier 3 | 0.024 | 0.022 | 0.035 | 0.004 | 0.032 | 0.009 | 0.001 | 0.564 | 0.001 | 0.018 | 0.018 | 0.022 | 0.012 | 0.209 |
Then, the performance score (\({\text{P}}_{\text{i}}\)) of the alternatives are determined using Eq. (6) and shown in Table 10.
Table 10
Suppliers | Performance score | Rank |
Supplier 1 | 0.885064 | 2 |
Supplier 2 | 0.647364 | 3 |
Supplier 3 | 0.970537 | 1 |
The ranking of the supplier organizations based on their GSCM performances, is as follows: Supplier 3 \(>\) Supplier 1 \(>\) Supplier 2. Supplier 3 secures the top position in ranking with the highest performance score (\({\text{P}}_{\text{i}}=\)0.970537) followed by Supplier 1 (\({\text{P}}_{\text{i}}=0.885064)\) and Supplier 2 (\({\text{P}}_{\text{i}}=0.647364)\) respectively. The performance score of Supplier 1 is satisfactory (\({\text{P}}_{\text{i}}=0.885064\)), whereas the performance score of Supplier 2 (\({\text{P}}_{\text{i}}=0.647364\)) is not up to the mark. Hence, Supplier 3 is the benchmark supplier. Other organizations should follow the strategies of Supplier 3 in order to enhance their performance.