Abstract
To address the issues of inaccurate expert weight allocation in existing large-group decision-making methods and information loss in multi-attribute group emergency decision-making processes, we propose a clustering-based method using the probabilistic hesitant fuzzy set. Recognizing the diverse contributions of the decision makers within each cluster-to-cluster consistency and the varied impacts of preferences in different clusters on overall group preference, we introduce a two-layer weight model. Specifically, from a two-dimensional viewpoint, we determine the weights of decision members within each cluster using an expert evaluation distance formula and the weights of each cluster using fuzzy entropy. Subsequently, by incorporating the Maclaurin symmetric mean operator (MSMO), we establish the ranking of decision alternatives. Finally, we assess the effectiveness and applicability of the proposed method by applying it to analyze the case of the Tonga volcanic eruption.
Keywords
Introduction
In recent years, there has been a significant increase in major natural disasters such as floods, earthquakes, fires, volcanic eruptions, and other catastrophic events. Among these, the eruption of Mount Taal in Batangas Province, Philippines, affected over 42,000 people [1]. The coal mine fire accident in Chongqing trapped 357 people [2]. Typhoon “Dussehra” has caused 1.4545 million people in the entire province to be affected, with an emergency evacuation of 363,000 people and resettlement of 150,000 people [3]. Influenced by factors such as climate change and certain human activities, the global incidence of disasters is rapidly rising. It is projected that by 2030, the frequency of large and medium-sized disasters worldwide will reach 560 occurrences annually, averaging 1.5 occurrences per day [4]. Probabilistic hesitant fuzzy set(PHFS) [5], as one of the effective representations of fuzzy information, expresses the membership degree of elements in a probabilistic form. This effectively reduces the problem of information loss in the decision-making process. Due to containing more information than ordinary hesitant fuzzy sets, research on probabilistic hesitant fuzzy sets is generally applied to large-group decision-making. To address the above challenges, the probability hesitant fuzzy set (PHFS) provides a more intuitive representation of experts’ risk preferences. PHFS incorporates probability distributions, introducing an additional layer of complexity to the modelling process. Specifically, significant advancements have also been made in the realm of distance metrics for PHFS [6–8]. As of now there is little research on expert weights,
The decision-making process involves an increasing number of DMs, each possessing unique areas of expertise and solutions. By classifying them accordingly, the resulting decisions can be more grounded in reality [9]. Kristina et al. [10] introduced the widely adopted K-means algorithm. Extending this algorithm, Zhou et al. [11] introduced the fuzzy C-means algorithm based on fuzzy membership degrees. Mengüç et al. [12] proposed a hybrid approach consisting of modelling and a K-means mathematical algorithm. Wang et al. [13] proposed a group decision consensus model based on two-dimensional binary linguistic terms. The weighting is based on the consistency level of judgment matrices provided by experts. The better the consistency of the judgment matrices, the higher the corresponding expert weights. Such methods only consider the quality of evaluations reflected in the logical consistency of experts during assessment, without accounting for the quality of evaluations based on the degree of alignment with objective reality. Therefore, when judgment matrices provided by various experts are entirely consistent, the weight coefficients for each expert are the same, making it impossible to differentiate the quality of individual judgment matrices. The above research has demonstrated the positive impact of PHFS in addressing decision problems. Nevertheless, PHFS solely consider DMs’ hesitations and fuzziness during the decision process, overlooking the urgency of unexpected events and the credibility of the information provided by decision experts in high-pressure situations. The proposed method in this paper includes the introduction of a weight model, which helps mitigate the impact of subjective weights, making the decision results closer to real situations. Moreover, this paper presents a decision model based on the PHFS environment, considering decision-makers’ hesitations, a factor that cannot be disregarded in emergency response scenarios.
The issue of expert weights is of utmost importance in group decision-making, Pang et al. [14] determined expert weights by comparing DMs’ assessments with the relative rankings of alternative solutions. In large-scale group decision-making. Methods for determining expert weights [15–17] often assume that the greater the difference between an individual and group opinions, the lower is the weight assigned to the individual. The above expert weight determination method is too simple and has certain limitations, which affects the credibility of the evaluation results. Therefore,
The literature review indicates that Multiple Attribute Group Decision Making (MAGDM) problems are applied in various aspects of life [18–26], and the integration of attribute information [27–31] has become a significant topic in MAGDM research.A review of the literature indicates that property information integration has emerged as a crucial topic of research on multi-attribute group decision-making (MAGDM).In real-world decision-making, the evaluation parameters of solution attributes are not mutually independent. Due to differences in decision-makers’ subjective consciousness, such as risk preferences, different decision results may arise, making it challenging to demonstrate the rationality of the outcomes. In such circumstances, the Maclaurin Symmetric Mean (MSM) operator is undoubtedly a favorable choice. The Maclaurin symmetric mean (MSM), initially proposed by Maclaurin [32], has undergone extensions and development [33] to capture the relationships among multiple input parameters. Furthermore, some researchers have integrated MSM into the fuzzy linguistic environment [34–36] to demonstrate the practicality and efficacy of property information integration. However, it is worth noting that in the context of emergency response,
In this paper we categorize DM weights into two parts, namely aggregation weights and internal member weights. These weights should differ for different aggregation preferences, primarily due to the varying number of internal DMs within the aggregation and the distinctiveness of the information each aggregation provides. Furthermore, in real-life scenarios, DM weights may fluctuate due to differences in knowledge structure, socio-cultural background, and familiarity with decision solutions. Therefore,
This paper proposes a clustering method based on PHFS by achieving three established research objectives. The effectiveness and applicability of the method are demonstrated through case analysis and comparative experiments with existing approaches.
We organize the rest of the paper as follows: Section 2 introduces the fundamental concepts of PHFS and the Maclaurin symmetric mean operator (MSMO). Section 3 presents the expert clustering model and the method for calculating expert composite weights. Section 4 delineates the specific steps for addressing emergency group decision-making problems. Subsequently, in Section 5, we conducted a case study to illustrate the application of the proposed method and provided a comparative analysis. Finally, Section 6 summarizes the paper.
The subsequent chapter will provide a comprehensive introduction to several pertinent concepts essential for the present study, building upon the aforementioned review of existing research.
Preliminaries
This section introduces the fundamental concepts of PHFS and the MSMO sorting approach, which will be used in the following sections.
Probabilistic hesitant fuzzy set
where i = 1, 2, ... , n, are all r-tuples in the ergodic combination 1, 2,..., n and
In this paper, the weight model is constructed for decision-making problems in PHFS environment, recognizing the diverse contributions of the decision makers within each cluster-to-cluster consistency and the varied impacts of preferences in different clusters on overall group preference, we introduce a two-layer weight model. Subsequently, incorporating the Maclaurin symmetric mean operator, we establish the rankings of decision alternatives. Therefore, in the following sections, how the model of this article is constructed will be shown in detail.
Compatibility-based clustering method
Given k experts evaluating m attributes of the solutions, the preference matrix R λ provided by the λ-th expert for the m attributes of the solutions is considered. First, use the Kendall’s intra-group data consistency analysis method, which involves conducting a consistency test on the judgment matrix. Subsequently, the normalized individual ranking vector T λ = (Tλ1, Tλ2, Tλ3, . . . , T λ m) S is obtained using R λ , where λ = (1, 2, . . . , k).
L (a, b) = 1 exhibits reflexivity; L (a, b) = L (b, a) shows symmetry; L (a, b) = 1 indicates that the individual ranking vectors of the a-th and b-th experts are completely compatible; For all a, b ≤ k, 0 ≤ L (a, b) ≤ 1. The closer L (a, b) is to 1, the more similar are the vectors Ta and Tb, vice versa.
In this paper we use the cosine value of the angle between vectors to represent the similarity between individual ranking vectors T a and T b as follows:
We summarize in Algorithm 2 the clustering of experts based on the similarity of compatibility in the expert vector matrix.
Expert clustering group weights model
Cluster the k decision experts participating in the decision-making process into M clusters and let G = { G1, G2, . . . , G
M
} (M > 1) be the cluster set, where cluster G
M
contains n
M
DMs and satisfies
Shannon [37] proposed the concept of information entropy in 1948, i.e.,
Higher entropy values indicate lower information content and result in smaller weight allocations, reflecting increased ambiguity and decreased impact on the decision outcomes. The formula for calculating the weights between groups is as follows:
In the context of MAGDM, there are K decision experts D l (l = 1, 2, . . . , K), Z attributes u i (i = 1, 2, . . . , Z), and expert weights ω D l (l = 1, 2, . . . , K). There are A candidate solutions P j (j = 1, 2, . . . , A). The scoring provided by the first expert for the j-th solution is expressed as D lp j , while D lu i is used for scoring the i-th attribute.
For experts, the discordance in the decision matrix indicates the level of uncertainty associated with their assessments of the available options. As discordance increases, trust diminishes, necessitating a reduction in their objective weights. Therefore, expert discordance functions O Z (D l ) and S A (D l ) are defined, along with objective weights ω D l as follows:
Expert D l gives attribute u i a score that affects the average separation rate of attribute u i scores.
For expert D l , the separation rate between the score of plan P j and the average score of plan P j is given.
Experts are known to have subjective weights of
The combined empowerment method is employed to determine the overall weight of the expert as follows:
By Definition 6, the PHFE geometric distance is
Among them, ω j represents the attribute weight.
The decision framework should be presented in Section 4, based on the newly proposed weight model and distance model in this section.
We summarize in Algorithm 3 the decision-making steps based on PHFS and the MSMO sorting approach.
In order to validate the effectiveness and superiority of the decision framework proposed in this paper, subsequent section will conduct case analysis and comparative analysis, accompanied by comprehensive discussions.
Case study
Problem description
Due to the complexity and variability of emergencies, it is challenging for any department or individual to make decisions independently. Therefore, emergency decision-making requires the simultaneous participation of multiple experts from different disciplines. Additionally, during the initial stages of emergencies, information is incomplete, decision-makers face time constraints, data scarcity, and their thinking tends to be ambiguous, preferring to express preferences using fuzzy information. Therefore, in a fuzzy environment, considering the challenges in emergency decision-making, methods such as fuzzy theory, multi-attribute decision-making, and group decision-making are chosen for solution selection. The volcanic eruption disaster in Tonga in January 2022 is an example of a complex and dynamic emergency event, requiring the simultaneous involvement of experts from various departments. Hence, using this case is suitable for validating the effectiveness and feasibility of the proposed method in this paper.
In order to safeguard people’s lives and basic livelihoods, the Tonga Prime Minister’s Office declared a state of emergency nationwide and immediately established the Accident Emergency Response Team. Relevant departments quickly set up the Emergency Decision and Rescue Command Center, convening experts from fields such as firefighting, medical, power supply, and environmental protection. Based on the actual situation, we select six emergency suppliers A ={ A i , i = 1, . . . , 6 }. To select the most reasonable plan, the government invited 50 emergency decision-making experts from different fields, i.e., K ={ k1, . . . , k50 }, to simulate the real scenario of a volcanic eruption. The decision-making process as follows:
DMs’ initial probability preference matrix
DMs’ initial probability preference matrix
Initial rating matrix for DMs
Initial rating matrix for DMs
Initial rating matrix for DMs
Initial rating matrix for DMs
According to the compatibility matrix, the experts are clustered according to the expert clustering steps, through data comparison, the calculated threshold T = 1.0000-0.9890 = 0.011 and the results are shown in Table 6.
Expert clustering results
Gathering the weights of internal decision-making experts
Comprehensive weight of each decision-making expert
DMs’ final probability fuzzy preference matrix
The weighted comprehensive value of each attribute
The aggregate value of each scheme
Comprehensive values at different r
From Table 12, it is evident that when not considering attribute weights, the ranking of solutions for the six logistics suppliers is A6> A4 > A2 > A1 > A3 > A5. Therefore, selecting the sixth logistics supplier is deemed the optimal solution. Meanwhile, due to the variation in the parameter r, there are subtle changes in the ranking of attribute values, indicating that the operator constructed in this paper is more flexible. This also demonstrates the stability of the proposed method. The numerical results validate the effectiveness of the proposed approach.
To showcase the adaptability and dependability of the proposed decision framework, we conduct a comparative experiment in this section. The two representative decision-making methods are selected for comparison based on the literature on multi-granularity linguistic large-scale group decision-making (LGDM) methods:
The multi-layer weight-solving multi-granularity linguistic LGDM method proposed by Wang et al. [38];
The attribute multi-granularity dual-layer weight LGDM method proposed by Xu et al. [39].
For ease of representation, we denote the proposed method and the three selected methods as Z1, Z2, and Z3, respectively.
Analysis of experiment results
The experimental results for methods Z1, Z2, and Z3 are presented in Tables 13 and 14.
Different workstation methods for aggregating weights
Different workstation methods for aggregating weights
Comparison of different decision-making algorithms
Through a comparison of the clustering weight calculation results in Table 13, it is evident that this study aligns with [38] and [39] in determining the most crucial rankings in the decision-making process. However, there are significant differences in the specific allocation of cluster weights. The reasons for these differences are as follows: The approach in [38] involves solving expert weights by constructing a trust matrix among experts; after clustering the expert group, the weights of the experts within each sub-cluster are summed to obtain the weight of each cluster. The method in [39] determines the cluster weights using the entropy method, leading to larger weights for clusters with fewer members, affecting the accuracy of the decision outcomes.
In contrast, we classify experts by first establishing an expert compatibility matrix, and then calculating clustering weights from the perspective of two-dimensional distance. We consider not only the comprehensive values of each PHFE but also the differences between their internal elements PHFN (both membership degree and occurrence probability influence the weights). Additionally, due to the variable parameter r, the decision results vary, making our approach more flexible, adaptable to different DMs’ needs, and thereby enhancing its generality. The comparative analysis above indicates that our proposed decision-making method is more flexible, reliable, and better suited for solving MAGDM problems with independent attribute values.
The effectiveness and superiority of the proposal in this paper will be demonstrated through case analysis and comparative analysis in this section. Subsequently, the subsequent section will provide a summary of the work conducted in this paper as well as future prospects.
The method proposed in this paper offers a new approach to solving MAGDM problems by considering the relationships between decision experts. In Section 2, we introduced the basic concepts of PHFS and the Maclaurin Symmetric Mean Operator (MSMO). Section 3 elaborated on the calculation methods for expert clustering models and composite weights of experts. Section 4 outlined the specific steps to address emergency team decision problems. Subsequently, in Section 5, we conducted a case study to illustrate the application of the proposed method and provided a comparative analysis. Finally, Section 6 summarized the paper. By constructing a compatibility matrix among the experts, we derive the decision experts’ weights, ensuring the rationality of decision expert weighting. In practical applications, our method can be used for emergency decision-making in sudden events, the selection of post-disaster management plans for natural disasters, assisting managers in decision-making, with significant practical significance and application value.
While advancing research on MAGDM, future work should address the following limitations: (1) We assume that the DMs are entirely rational and neglect their psychological behaviors; improving our method could involve accounting for DMs’ bounded rationality. (2) Limited datasets may hinder a comprehensive understanding of the superiority of our proposed method; future research should incorporate additional datasets and conduct statistical analyses to ascertain its advantages. Additionally, this paper focuses on the scenario where the weights of solution attributes are known. In the future, we will delve into the exploration and research of situations where the weights of solution attributes are unknown.
Funding
This research was supported in part by the National Natural Science Foundation of China (Grant No. 11971434), Zhejiang Provincial Natural Science Foundation of China (Grant No. LY21G010002), the Fundamental Research Funds for the Provincial Universities of Zhejiang (Grant No. XT202308), and the Modern Business Research Center of Zhejiang Gongshang University, which is a key Research Institute of Social Sciences and Humanities of the Ministry of Education of China.
