Abstract
The purpose of this paper is to explore how port enterprises can scientifically select a better logistic service provider (LSP) to achieve a high efficiency. An empirical study is conducted to verify the effectiveness of the combination weighting-grey synthetic decision-making method by helping the LSP selection of a port enterprise in China. Data are collected from questionnaires administered to port logistics’ industry professionals. The method is proposed, which associates the analysis network process method with the entropy method to determine the combined weights of the evaluation indexes. The improved centre-point triangular whitenization weight function is introduced to cluster the alternative port LSPs and judge the corresponding grey classes. Subsequently, the synthetic weighted decision-making vectors are used to determine the grey synthetic decision-making coefficient vectors. The grey synthetic clustering decision-making coefficients are calculated to establish a synthetic decision-making rank of the alternative plans. The combined method can help the port enterprises realize the selection of better LSPs in a scientific manner.
Introduction
With the globalization of the economic market, logistics is now seen as a key area in which industries can cut costs and improve their customer service quality [1]. Each outsourcing company has its unique needs for the logistics support from a provider [2]. The reasonable selection of logistics service providers (hereinafter referred to as LSPs) is one of the key issues that enterprises need to address. Generally, the decisions of the enterprises are often unclear and cannot be estimated as an exact numerical value. Thus, realizing a better selection of LSPs is difficult and challenging. Due to the uncertainty of the evaluation process, the problem exhibits a grey character, thereby becoming a complex multiple attribute decision-making problem [3]. Currently, the LSPs of the port enterprises in China are mainly small and medium sized. The overall strength and operation standardization degree of these LSPs is not sufficiently high. In addition, in some cases, the quality of the logistics services provided cannot satisfy the requirements of the port enterprises. Therefore, studying the selection strategy of the LSPs of port enterprises has a certain practical significance to improve the operation efficiency and operation level of the port enterprises.
Many scholars have performed relevant studies in this domain and attempted to solve this problem. Different types of methods have been applied or developed to evaluate the selection of the LSPs considering different aspects. Such methods include analysis network process method (ANP), entropy method, fuzzy Delphi method, grey clustering method, double-layer planning model, combination of the grey relational analysis and the technique for order preference by similarity to ideal solution (TOPSIS) method, combination of the entropy method and the G1 method, and empirical studies. The methods that have been applied in the literature to evaluate and select the LSPs are summarized in Table 1, and further details can be found in [4]. This table also presents the most recently conducted studies. Some scholars used methods other than those mentioned above to study the LSP selections. For example, [5] applied structural equation modelling to test the conceptual model based on the survey data from 245 Chinese third-party logistics (3PL) providers. [6] introduced a fairness entropy function to establish a new game model for determining the optimal number of multifunctional LSPs. Asian et al. [7] used a new method based on the Kano model for evaluating and indexing 3PL providers. Goker [8] introduced an integrated cognitive map-based intuitionistic fuzzy multiple criteria decision aid to rank agile outsourcing provider alternatives and then determine the best performing one. Ilgin [9] proposed a novel third party reverse logistics providers (3PRLPs) evaluation methodology combining linear physical programming (LPP) and fuzzy programming (FP), which considers the uncertainty of budget allocation and capacity, and the determination of 3PRLP order quantity. These authors found that the uncertainty, order frequency, and transaction size, but not the asset specificity, were significantly associated with the third-party purchasing.
A summary of methods for LSP selection
A summary of methods for LSP selection
Grey systems theory initiated by Deng [44] is suitable for uncertain and small systems that include many decision makers [45]. This theory has made several contributions to numerous economic applications from various fields such as supply chain management, decision-making processes, and financial performance evaluations [46]. In recent years, grey systems theory has been applied by many researchers to solve the LSP selection problem. Chen et al. [47] combined grey relational analysis and TOPSIS methods and proposed a combination weighting GI-TOPSIS method to realize the selection of the logistics providers. Zhou [48] proposed a multiple objective decision-making model based on grey clustering and entropy weight methods to select the best provider. Rajesh and Ravi [49] used the grey relational analysis method to choose providers and considered the change in the weights to study the sensitivity of the change in the selection results. Pitchipoo et al. [50] combined the entropy method with principal component analysis to solve weights; subsequently, the grey relational analysis method was used to select the providers. Parkouhi et al. [51] proposed Grey Simple Additive Weighting technique (GSAW) to determine the score of each supplier. In general, there is a tendency to combine gray system theory with other decision-making methods for selecting LSP.
However, several shortcomings remain in the selection of the LSPs. For example, the index system cannot accurately reflect the interdependence relationship among the indexes; the manner of solving the index weights relies excessively on expert judgement and other subjective factors, and the degree of attention to objective factors is not sufficiently high; and the manner of handling the grey character of the problem is not appropriate. In this paper, LSP evaluation index system is determined by service quality, business ability, logistics cost, enterprise soft power and cooperation. ANP is used to determine the subjective weight, which is beneficial for the index weight value to fully consider the experts’ professional judgments. Besides, the entropy method is used to determine the objective weight, which reflects the significance of objective factors of evaluation index data. In addition, the calculation of the grey clustering coefficients is determined by using the improved center-point triangle whitenization weight function, which reflects properly handling the grey characteristics of this problem. Accordingly, a combined weighting-grey synthetic decision-making method is proposed, which can help enterprises solve the problem of selecting LSPs, and the effectiveness of the decision-making method is verified through empirical research.
The paper is structured as follows: In Section 2, we constructed and analyzed the LSP suppliers’ evaluation index. In Section 3, combination weighting-grey synthetic decision-making method is proposed to solve the problem of selection of LSP suppliers. In Section 4, a practical example is shown to the effectiveness and the sensitivity analysis on the objects is carried out also. Finally, a conclusion is given in Section 5.
Preliminary creation of the evaluation index system
Supplier selection is mainly composed of two aspects: development the index system and researching the selection method. The index system should be systematic, simple, comparable, flexible, independent, dynamic, scientific, efficient, general, and a combination of qualitative and quantitative principles. Li et al. [52] evaluated and chose procurement logistics service providers in the IT industry using the C2 R DEA model and they examined the index system of these providers from five perspectives: business level, resource level, service level, cooperation level, and information level. To assess and choose third-party logistics service providers for medical equipment, Zhang et al. [53] built an evaluation index system based on four factors: basic resources, business operation, monitoring management, and human resources. The five factors of commitment, competence, communication, creativity, and customization, as well as coordination and collaboration, were part of the 5 C framework that Gupta and colleagues [54] proposed. This framework further clarified how the best LSP should be chosen based on the ongoing quality of service. For an enterprise to grow, its soft power is crucial, which also holds for LSP. This paper divides the evaluation factors influencing the choice of LSP for port enterprises into five first-level factors based on a literature review: service quality, business ability, logistics cost, enterprise soft power, and cooperation. This paper further differentiates the first-level indicators into certain second-level indices by the literature of Li et al. [55], Senthil et al. [56], Asian et al. [57], and Huang et al. [58]. To further define the indicators, this paper specifically selected the qualitative or quantitative indicators, as indicated in Table 2.
Preliminary evaluation index system and evaluation data for the LSP
Preliminary evaluation index system and evaluation data for the LSP
According to the preliminary construction of the index system, a survey related to the importance of the evaluation index was designed. A total of 140 copies were delivered to the professionals of the port logistics industry. Subsequently, 132 copies were recovered, of which 120 were valid questionnaires; 12 questionnaires were removed, as some of the questionnaires were not completed, and the others had the same answers. The valid return rate was 85.71%.
The effective SPSS 22.0 software was used to collect the data for the statistical analysis. The main statistical scores of minimum and maximum values and the average and standard deviation of each index are listed in Table 3. A higher index score means that it is more important in the selection of the port enterprise LSP.
Statistical summary of the questionnaire for the importance of the evaluation indexes
Statistical summary of the questionnaire for the importance of the evaluation indexes
Most of the indicators have more than 7 points, and the standard deviation of these values is approximately 1. The following indexes with relatively low scores and relatively large standard deviation values were removed: value-added services, service flexibility, packaging cost, logistics information and management costs, demand analysis ability, scheme design ability, service innovation capability, working experience, corporate culture, and cultural compatibility.
Next, the reliability and validity of the remaining 20 indexes were analysed.
Reliability analysis
The reliability is used to represent the stability and consistency of the test results when the measurement is repeated. This aspect has a decisive influence on the reliability of the contents of the questionnaire to ensure the reliability and stability of the questionnaire content and the accuracy of the results of the questionnaire analysis. Under ordinary circumstances, the internal reliability of the scale, that is, the internal consistency between the items of the questionnaire, is mainly investigated to test the correctness of the obtained conclusions.
In this paper, we consider the comparison of the internal consistency reliability by using the commonly used Cronbach coefficient (Cronbach’s α) method that initiated by Cronbach & Gleser [59] to analyse the reliability of the questionnaire. The alpha coefficient is between 0–1. A larger alpha coefficient corresponds to a greater credibility of the questionnaire. It is generally believed that a reliability coefficient of 0.7 or above is acceptable.
The reliability analysis indicated that the overall reliability coefficient of the questionnaire was 0.738. Consequently, the internal consistency and reliability of the questionnaire are satisfactory.
Validity analysis
The validity corresponds to the correctness of the results measured using measurement tools or means to reflect the degree of the tested objects. A higher validity indicates a higher consistency with the test results. In this paper, the structural validity of the questionnaire was analysed.
As shown in Table 4, the eigenvalues of 5 factors are greater than 1; these factors together account for 66.947% of the total variance, and further analysis of the factor square load after rotation indicates that the 5 main factors contributed considerably to the interpretation of the overall sample. Consequently, the questionnaire can be considered reasonable.
The factor load matrix, which is rotated using the orthogonal rotation method, is presented in Table 5.
Results of total variance
Results of total variance
Factor load matrix after rotation
According to the validity analysis results, the evaluation indexes were grouped into the following five first-level index groups: service quality, business ability, logistics cost, enterprise soft power, and cooperation. Thus, the index system for the selection of the logistics service providers of the port enterprises is established, as given in Table 6.
Index system for selection of logistics service providers of port enterprises
Service quality
The core product of the port LSP in the supply chain operation is the port logistics service; therefore, the quality of the logistics service is an evaluation index that must be considered.
Furthermore, it should be noted that because the port enterprise has not yet established a strategic partnership with the port LSP, only a preliminary knowledge of the former service quality of the LSP is taken as a reference.
(1) Customer satisfaction rate
In the present buyers’ market, customer satisfaction is one connotation of the supply chain management in the 21st century. In the selection process of the LSP, the customers refer to the core enterprises served by the port logistics service providers. Customer satisfaction is a subjective index, which represents the differences between the expected and actual levels of the LSP. In actual evaluation, we selected the port enterprises that are being served currently or have been served previously by the port LSP as the investigation objects and designed the questionnaire for customer satisfaction. The customer satisfaction is calculated using formula (1) with the data from the returned questionnaires.
In formula (1), CS denotes the customer satisfaction, N denotes the number of the returned valid questionnaires, Si denotes the marks of the valid questionnaire i, and S denotes the full marks of the questionnaire for the customer satisfaction.
(2) Order completion rate
The order completion rate reflects the ability of the LSP to complete the order and directly reflects the reliability of the supply chain. The characteristic of the order completion rate is that the service provided by the supplier is consistent with the customer’s requirement. The rate can be calculated using formula (2).
(3) On-time delivery rate
The on-time delivery rate refers to the timeliness of the LSP to provide logistics services. This rate corresponds to not only the real capacity of the logistics enterprise to meet the customer demand but also to the integrated scheduling management capabilities of the logistics service provider. Therefore, a higher index corresponds to a higher level of enterprise management.
(4) Product integrity rate
The product integrity rate refers to the product in the logistics process and its maintenance of the overall integrity of the ratio, reflecting the implementation of service control by the logistics enterprises. Improving the product integrity rate plays a key role in improving customer satisfaction.
(5) Problem handling rate
The core enterprise attaches considerable importance to the problem handling rate of the port logistics service provider. This rate reflects the supplier’s ability to solve problems in time when encountering problems in the provision of the logistics services. Therefore, it is of significance to establish a suitable corporate image of dealing with problems in the logistics service. The calculation formula for the problem handling rate is given in formula (5).
In the choice of an LSP, from the point of view of the port enterprise or the customer, a satisfactory business service capability is the premise to judge whether the supplier is eligible. In the complex logistics environment, satisfactory logistics business ability enables enterprises to promptly meet customers’ needs and effectively address challenges and risks.
(1) Business diversity
The business diversity refers to the diversity of services provided by the logistics services suppliers. A more extensive business scope and more service types offered correspond to a more comprehensive business ability of the supplier. With a stronger ability to meet customer demands, the supplier can provide better services for the enterprises.
(2) Logistics network
The logistics network reflects the logistics hierarchy of the suppliers. The business level of a port LSP is not only reflected in port logistics but also in the required cooperation with aviation, road and railway transportation, etc. Therefore, the corresponding multimodal transport capacity and logistics network structure also reflect the business level of the suppliers. The logistics network is a qualitative indicator that can be obtained by the method of grading.
(3) Operation management ability
The operation management ability refers to the ability of the LSP to handle various operational activities during service provision, such as human resource planning, the coordination of resource allocation, and controlling equipment and facilities. The core aspect of the operation management ability is to design the service process with a high performance, turning a limited resource input into an efficient output. Providers with excellent operation management ability can considerably save resources, reduce costs and improve efficiency.
(4) Risk coping ability
The risk response ability refers to the ability of the logistics enterprise to deal with strain when facing unexpected situations. An LSP may be affected by the internal and external environment, such as typhoons, tsunamis, earthquakes and the enterprise’s internal problems and other factors, resulting in the disruption of the logistics services supply. Therefore, the logistics enterprises must have a suitable risk response capacity. This ability is a qualitative indicator, which can be obtained by the method of grading.
Logistics cost
The logistics cost is an important index when an enterprise selects a logistics service provider. If the logistics cost is reduced, the total cost of the enterprise is also reduced, which makes the product more competitive, and the main reason enterprises choose an LSP is to reduce the cost of logistics in addition to risk transfer.
(1) Transportation cost
The transportation cost constitutes an important part of the enterprise logistics cost, including the energy consumption, transportation vehicles, transport personnel and other related costs. The transportation costs can reflect the market competitiveness of a logistics enterprise. This indicator is the dominant cost, which is relatively easy to measure. Further, the transportation cost is a quantitative indicator, which needs to be measured according to the characteristics of the enterprise product, and one can obtain the corresponding data through the logistics enterprise.
(2) Storage cost
The storage cost refers to the cost incurred by the LSP to provide warehousing services for the enterprises. The storage cost is an important part of the logistics cost and has a direct impact on the level of the logistics costs. Most storage costs vary not with inventory levels, but with the number of storage locations. The storage cost mainly refers to the cost of an enterprise leasing the warehouse space of the logistics service provider and the cost of the various types of storage operations.
(3) Circulation processing cost
The circulation processing cost refers to the cost of processing products to improve the logistics efficiency when an LSP provides logistics services for the enterprises. This cost mainly includes the circulation processing packaging, materials and labour costs.
(4) Handling and carrying costs
The handling and carrying costs refer to the costs incurred by the LSP in helping the enterprises in the logistics work and handling the sum of expenses generated by the direct and indirect costs of handling. These costs mainly include the labour costs, cost of machinery use, energy consumption and other related costs.
Enterprise soft power
(1) Market share
The market share is the proportion of the logistics enterprises in the market, that is, the market share reflects the existing market share and development potential of an LSP. A greater market share corresponds to a greater ability of the logistics service provider to control the market. This share is a sign of the soft strength of the logistics enterprises.
(2) Enterprise qualification
To distinguish the situation of the logistics enterprises and allow the customers to obtain a comprehensive understanding of the domestic logistics enterprises, China performed a grade evaluation to assess the domestic logistics enterprises. The rating of the domestic logistics enterprises are divided into five grades: A, AA, AAA, AAAA, AAAAA, of which the 5A level is the highest level of qualification. The enterprises with a higher qualification ranking have a stronger comprehensive competitiveness.
(3) Enterprise reputation
The enterprise reputation of an LSP represents the society’s and customer’s recognition towards the enterprise. The reputation of an enterprise can more intuitively reflect the strength of a business level in its industry. Port enterprises tend to value the enterprise’s reputation more when choosing an LSP. The reputation is a qualitative indicator, which can be obtained by the method of grading.
(4) Professional talent ratio
The professional ratio of the port logistics of a port LSP reflects its level of human resources in the area of port logistics. This ratio can be calculated using formula (7).
(1) Cooperation success rate
The cooperation success rate refers to the number of successful instances of cooperation between the port LSP and the core enterprises of other ports in the past. This element shows the ability of the supplier in terms of cooperation, the cooperation performance and the level of cooperation. The calculation formula is as follows.
(2) Informatization degree
The enterprise informatization degree is the basis for realizing a prompt response of the supply chain, and it is also the basic premise to realize information sharing. Logistics enterprises apply advanced management information systems and the human, financial, material and other integrated information management systems of the enterprise to realize internal and external information sharing. A high or low level of informatization degree is a crucial factor to be considered when selecting the LSP for the port enterprises.
(3) Communication level
Effective communication is the precondition and guarantee for cooperation. Therefore, a port LSP should possess excellent communication skills and maintain close communication with the commissioned enterprises. Furthermore, the LSP should ensure that both sides can receive feedback in a timely and effective manner.
The pronounced advantages of the combination weighting-grey synthetic decision-making method includes: 1) using ANP to determine the subjective weight is beneficial to fully consider the expert’s professional judgments, 2) using entropy method to determine the objective weight, which reflects the significance of objective factors of evaluation index data, 3) using the calculation of grey clustering coefficient to determine the improved central-point triangle whitenization weight function, which reflects properly handling the grey characteristics of this problem.
There exist m alternative plans in the logistics service market, and n evaluation indexes for the evaluation of the alternative plans. The evaluation data for the alternative plans i (i = 1, 2, . . . , m) pertaining to the evaluation indexes j (j = 1, 2, . . . , n) are represented as x ij (i = 1, 2, . . . , m ; j = 1, 2, . . . , n). This paper contains a total of s grey classes. w j = (w1, w2, . . . , w n ) represents the combined weight of each evaluation index. The decision steps of the combination weighting-grey synthetic decision-making method are as follows.
Combination weighting
We consider the combination weight composed of the subjective weights by using the ANP method and the objective weights by using the entropy method to comprehensively reflect the importance of the evaluation indexes.
Determination of subjective weights based on the ANP method
(1) ANP network structure
According to the size of the controlling force, the system elements in the ANP network structure are divided into the control layer and the network layer. The control layer has a decision-making objective. According to the various decision-making problems, the control layer can also contain a number of decision-making criteria, which are assumed to be independent from each other. The network layer is composed of the elements and influence relationships controlled by the control layer. Depending on whether the interactional elements belong to the same cluster or if the influence is bidirectional, the influence relationships are divided into the inner dependence, outer dependence and feedback. A typical ANP network structure is shown in Fig. 1.

ANP network structure.
(2) Construction of the unweighted supermatrix
To reflect the complex and multiple influence relationships among the elements in the network layer, the ANP approach uses various supermatrices as the modelling tools for determining the influence relationships, in which the construction of the unweighted supermatrix is the operational basis.
We assume that the control layer of the ANP network structure has a total of M decision-making criteria (P1, P2, ⋯ , P
M
). The decision-making criteria of ANP are determined by the objective of the decision problem. All the decision-making criteria are independent of each other, from which sub-criterion elements under its decision criterion layer can be established. The network layer has N clusters that have interactions, denoted by C1, C2, ⋯ , C
N
, and the elements in cluster C
j
are denoted by ej1, ej2, ⋯ , e
jn
. Among these elements, some may be influenced by not only the elements from the same cluster, namely, the inner dependence, but also the elements from other clusters, namely, the outer dependence. For example, if the element e
jk
(k = 1, 2, ⋯ , n
j
)in cluster C
j
is influenced by the elements in cluster C
i
, according to the size of the local influence of the elements in cluster C
i
on e
jk
, we can use the 9-scale method to construct a pair-wise judgement matrix with respect to a certain criterion and sub-criterion e
jk
and derive a normalized weight vector, denoted by
(3) Construction of the weighted supermatrix
The block matrix
Let the clusters that have one or more elements influencing ejk in C
j
be denoted by set gjk. Consequently, the clusters in set G
j
= gj1 ∪ gj2 ⋯ ∪ gjk ⋯ ∪ gjnj are the clusters that influence C
j
. Thus, with respect to the sub-criterion C
j
, we need to construct a pair-wise judgement matrix to compare the clusters in G
j
and obtain the normalized weight vector, which relates the influence priority of these clusters, denoted by
After weighting the unweighted supermatrix W by using the weighted matrix A, we can obtain the weighted supermatrix
(4) Limit processing of the weighted supermatrix
The complex and multiple influence relationships between the elements in the network layer, including the direct and indirect influences, complicate the comparison of the global influence priority of these elements. Thus, the ANP approach derives the limit matrix through the limit processing of the weighted supermatrix. The limit processing of the weighted supermatrix is equivalent to a Markov process, in which the influence relationships are transmitted and overlaid through constant iterations. Therefore, the steady global weight vector is obtained when a steady state is attained. It can be proved that the limit matrix exists in a network structure that simultaneously possesses an inner dependence and feedback, and any column of the limit matrix is a steady global weight vector.
Entropy method has the important characteristic of reflecting the degree of information uncertainty. Entropy method is used by many scholars to determine attribute weights. Garg [60] proposed a new strategy which uses different entropy values and unknown attribute weights to solve multi-attribute decision-making problems. Garg [61] used entropy functions to calculate the attribute weight vectors exploited to aggregate the preferences of decision makers. Wang, Gar and Li [62] defined a Pythagorean fuzzy entropy measure, established a method to determine the attribute weights and explored a novel approach to manage multiple attribute decision making problems. In this paper, the objective weights of the evaluation indexes are determined by using the entropy method. As this method depends only on the information of the objective evaluation data of the alternatives, the weight determined by the entropy method is termed as the objective weight. The basic steps of the objective weight determination by the entropy method can be described as follows:
(1) Construction of the original evaluation data matrix
Suppose that there exist m alternatives, and the evaluation index system has n evaluation indexes. The original evaluation data matrix is labelled X (x
ij
represents the original evaluation data of the ith alternative pertaining to the jth evaluation index).
(2) Construction of the standardized evaluation data matrix
Considering the evaluation indexes that are different in dimension and the assessment criteria, the original evaluation data matrix cannot be directly used in the multiple attribute decision-making process. Based on formulas (9) and (10), the original evaluation data matrix is transformed into the dimensionless standardized evaluation data matrix R.
If the index is negative, the standardization formula would be as follows:
(3) Calculation of the entropy value
The formula for calculating the entropy value is as follows:
when
(4) Calculation of the entropy weight
The formula for calculating the entropy weight is as follows:
In this paper, to amplify the difference in the importance between the evaluation indexes, the combined weights of the evaluation indexes are determined by using the product method. The calculation formula is as follows:
Determination of the turning points or centre points of the grey classes of the evaluation indexes
The values of the hypothesis evaluation indexes j lie between [a
j
, b
j
]. According to the overall evaluation requirements, the evaluation indexes are divided into a total of s grey classes. Next, the turning points
Creation of the whitenization weight functions of the corresponding grey classes
The grey classes 1 and s are constructed considering the corresponding whitenization weight functions

Schematic diagram of the improved centre-point triangular whitenization weight function.
Using formula (17), we can calculate the grey clustering coefficients
The order of the normalized grey clustering coefficients of alternative plans i for grey classes kis
Calculation of the synthetic weighted decision-making vectors
It is assumed that the total existing s grey classes,
Formula (19) can be used to calculate the initial grey synthetic decision-making coefficients of the alternative plans i for grey classes k, and
After the normalization process, we can obtain
The weight vector of the grey synthetic clustering decision-making coefficients is γ = (1, 2, . . . , s - 1, s) T . Using formula (20), the calculation can be performed by using the grey synthetic clustering decision-making coefficients π i of alternative plans i.
Because
By comparing the size of the grey synthetic clustering decision-making coefficients of alternative plans i in the same grey classes k, we can conduct a synthetic decision-making ranking process.
In this paper, the decision maker can utilize the combination weighting-grey synthetic decision-making method to solve the problems of selecting LSP of port enterprises. Firstly, by analyzing the present situation of the port enterprise’s logistics business, the combination weighting method was used to obtain the combination weights of the LSP evaluation. Besides, determing turning points or centre points of the grey classes of the evaluation indexes to build the whitenization weight functions corresponding to the grey classes. What’s more, calculating the grey clustering coefficients to judge providers corresponding to the grey classes. Finally, the comprehensive weighted decision vector and grey comprehensive clustering decision coefficient are calculated, and the comprehensive ranking is carried out to select the LSPs that are more suitable for the port enterprises.
Empirical Study
When choosing an LSP for a port enterprise, there are several factors to take into account. In order to reflect the objective components of a quantitative indicator, such as customer satisfaction rate, it is important to calculate the objective weight using the entropy value approach. Business diversity is a qualitative indicator; therefore, in order to calculate the subjective weight that best reflects the opinion of the indicator’s experts, one must utilize the ANP. Therefore, it is important to take into account both the subjective and objective weights of the port enterprise while analyzing each indicator of each LSP and to determine the combination weights that were generated using the combination weighting. Port enterprise A mainly produces various concrete blocks and prefabricated components. These products are widely used in port and waterway engineering and in buildings, roads and other constructions. Due to the limitation of the allocation of funds, the enterprise decides to select an LSP to help them address the inbound and outbound logistical aspects. The selection and evaluation of the alternative providers are based on the combination weighting-grey synthetic decision-making method. The evaluation data of each alternative provider are presented in Table 7.
Evaluation index system and evaluation data of the LSP
Evaluation index system and evaluation data of the LSP
By using the combination weighting method, the combined weights of the evaluation indexes of the LSP are obtained, and the results are presented in Table 8.
Combination weights of the evaluation index and grey class classification of the LSPs
Combination weights of the evaluation index and grey class classification of the LSPs
The results appeared in Table 8 show that in the service quality index, on-time delivery rate is more important. Besides, the operation management ability is the most important of business ability index. What’s more, the transportation cost is the most significant of logistics cost index. Otherwise, in the enterprise soft power index, enterprise qualification is more important. Last but not least, informatization degree is most crucial of cooperation index.
Determination of the turning points or centre points of the grey classes of the evaluation indexes
According to the evaluation requirements, the evaluation indexes of the LSP are divided into 4 grey classes: poor, medium, satisfactory and excellent, as shown in Table 7.
Construction of the whitenization weight functions corresponding to the grey classes
Taking the customer satisfaction rate as an example, the corresponding triangular whitenization weight functions of a lower measure
Calculation of the grey clustering coefficients
The grey clustering coefficients for each alternative provider are calculated, and the results are summarized as shown in Table 9.
Grey clustering coefficients of the providers
Grey clustering coefficients of the providers
By observing the maximum value of the grey clustering coefficients for each alternative provider, the providers belonging to the grey classes can be evaluated, and the results are presented in Table 10.
Providers corresponding to the grey classes
Providers corresponding to the grey classes
This paper considers four types of grey classes, which can be used to calculate the synthetic weighted decision-making vectors of grey classes k. According to Formula 18, four grey classes can be calculated as follows.
Calculation of the grey synthetic decision-making coefficient vectors
The initial grey synthetic decision-making coefficient vectors of the alternative providers i for grey classes k are calculated. After the normalization process, the grey synthetic decision-making coefficient vectors matrix can be obtained:
Calculation of grey synthetic clustering decision-making coefficients
The grey synthetic clustering decision-making coefficient of each alternative provider is obtained, as shown in Table 11.
Grey synthetic clustering decision-making coefficients of the providers
Grey synthetic clustering decision-making coefficients of the providers
In this paper, the combination weighting-grey synthetic decision-making method is applied to the empirical research of LSP selection of port enterprise. This method can effectively distinguish and rank the LSPs of the port enterprises.
According to the results presented in Tables 9 and 10, G2 belongs to the medium grey class; G1 and G5 belong to the satisfactory grey class because 2.673 > 2.593, and thus, G5 is better than G1; G3 and G4 belong to the excellent grey class because 2.840 > 2.760, and thus, G3 is better than G4. The final ranking for the alternative providers is G3 > G4 > G5 > G1 > G2. This result shows that provider G3 has the largest grey synthetic clustering decision-making coefficient, and provider G4 ranks second. From a different perspective, provider G2 is relatively poor. Therefore, the port enterprise should choose provider G3 as its service provider.
In order to test the reliability of the weighting-grey synthetic decision-making method proposed in this paper, the ANP method and the grey clustering method are selected to solve the same problem to investigate the consistency between the evaluation results. It can be seen from Table 12 that the method proposed in this paper is highly consistent with the evaluation results of the other two methods in LSP selection, which further verifies the reliability of the method proposed in this paper.
Comparison of evaluation results
Comparison of evaluation results
In Table 12, the ANP method alone would place an undue reliance on subjective elements like expert judgment. Sometimes the results of the grey clustering method alone do not adequately reflect the results of the clustering. Combining the ANP, entropy approach, and grey decision procedure to get at an acceptable multi-criteria decision-making solution. It is appropriate for assisting decision-makers in circumstances where they are lacking information and have a strong sense of subjectivity by supplying pertinent information for making decisions. This weighting-grey synthetic combination decision-making approach has the advantages listed below: First off, by using ANP to determine subjective weights, it is simpler to fully incorporate expert expertise into the index weight values. Furthermore, the relevance of objective aspects in the assessment index data is also reflected in the objective weights, which are determined using the entropy value approach. Additionally, the enhanced center point triangle whitening weight function is used to calculate the grey clustering coefficients, reflecting the proper handling of the problem’s grey characteristics. Moreover, the analysis’s findings are highly reliable.
Since this method combines the ANP method and the entropy method to determine the combination weights of evaluation indexes, it was reasonable to analyze the sensitivity of the weighted grey synthetic decision-making method. This implies that we consider how a standard weight change affects the terminal ranking of logistics supplier alternatives. Nevertheless, owing that the sum of all criteria equals to 1, if the weight of the p-th criterion changes Δp, weights of other criteria change Δj.
Table 13 shows the impact of changes in the weight of service quality, business ability, logistics cost, enterprise soft power, and cooperation on the ranking of LSP alternatives. Columns 1, 3, 5, 7 and 9 respectively show the specific changes of the index weight of service quality (Δ1), business ability (Δ2), logistics cost (Δ3), enterprise soft power (Δ4) and cooperation (Δ5). Corresponding to Δ1 to Δ5, column 2, 4, 6, 8 and 10 respectively represent the LSP ranked first under the new weights.
The effect of changes in weights for the criteria indicators
When the standard weight is increased by 0.1 and 0.2 and decreased by 0.1 and 0.2 respectively, the sum result is 0. Among them, the weight changes of the three indicators, business ability (Δ2), enterprise soft power (Δ4), and cooperation (Δ5), did not affect the ranking of the best suppliers. When the weight value of service quality (Δ1) is increased by 0.2, it will have a certain impact on LSP ranking. When the weight value of logistics cost (Δ3) is reduced by 0.1 and 0.2 respectively, it will have a certain impact on LSP ranking.
Therefore, through the sensitivity analysis, we can see that the business ability, enterprise soft power and cooperation meet the stable standards. The change of service quality and logistics cost will lead to the change of supplier ranking, and the stability is relatively low.
The selection of an appropriate LSP is an important strategic decision and plays a substantial role in establishing long-term relations between the LSP and the port enterprise. This paper conducts a literature review on the grey systems theory and entropy method used in LSP selection. By performing the analysis of the reliability and validity of the questionnaire, this paper determines the index system for the evaluation of the provider. Subsequently, the ANP method and the entropy method are combined to determine the combined weights, and the improved centre-point triangular whitenization weight function is used to cluster the alternative plans. Finally, the grey synthetic clustering decision-making coefficients are calculated to determine the synthetic decision-making rank of the alternative plans. The validity of this method is proven through empirical research. Compared with the ANP method and the grey clustering method, the results are consistent. It shows the reliability of combination weighting-grey synthetic decision-making method in LSP selection. From the perspective of implementation, the proposed approach can also solve the problems of pattern recognition as well as the evaluation of medical and health services.
There exist certain limitations in the interpretation of the results obtained using the proposed approach. Methodologically, the data collected are based on a self-assessment from the professionals of the port industries. In terms of the scope of this study, these questionnaires were collected only from mainland China, which may limit the generalizability of the results to other regions. In future studies, we will conduct similar studies on the selection of LSP in the presence of deterministic data and fuzzy data. The selection method of LSP will be considered to improve and classify, and it will be extended to other regions with different cultural and social backgrounds to solve more practical problems [63-65].
Footnotes
Acknowledgments
This work was supported by National Natural Science Foundation of China under Grant 71601050.
Conflict of interest
The authors declare no potential conflict of interest.
