Abstract
In recent years, supply chain risk management has been followed with interest due to the short life cycle of products. How to identify risk indicators can help evaluate risks on supply chains. Commonly adopted methods such as Fuzzy to determine the level of risks have limitations. In this paper, a framework of supply chain risk evaluation is first proposed and risk indicators are identified by theoretical surveys from 35 keywords and empirical analysis from 448 questionnaires. Moreover, both linguistic risk assessment model and Cloud model are used to evaluate risks of supply chain. The Cloud model evaluation results are between general risk and high risk but closer to high risk. In addition, Cloud expected value of risk is 6.54 which is within the high-risk range, and evaluation results are also high risk. It is shown that when the weights are the same, the cloud model can determine the priority of risk indicators, and reflect volatility and randomness comparing with other evaluation methods.
Introduction
As a new type of management, supply chain achieves the unification of logistics, capital flow and information flow by coordinating its upstream and downstream enterprises [1]. Production and sales are not only the rules of the entire supply chain but also represent the integration of supply chain [2, 3]. Moreover, globalization and short life cycles of products lead to a more complex supply chain.. Traditional approaches to supplying chain management have undergone tremendous changes [4]. Although this shift of supply chain has enabled companies to compete effectively in their business 7 environment [5, 6], it has made supply chains more fragile [7]. Facing increasingly fierce competition environment, it is necessary to deal with the risks that may arise in the pursuit of efficiency in supply chain.
Based on the above facts, how to identify and evaluate risks will help to build a flexible supply chain network [8]. However, most of existing evaluation methods are using AHP-Fuzzy model and the ambiguity of risk factors is not well reflected. In actual evaluation, both selection of evaluation domain to calculate weight and generation of comprehensive evaluation matrix are randomness and uncertainty. This study tries to use Cloud model to substitute AHP-Fuzzy membership function to evaluate the risk in supply chains, especially the fuzzy and random of risk assessment model.
The purpose of this study is to establish a supply chain risk indicator system according to supply chain management theory and supply chain risk management theory, and specially, and to propose a Cloud model for supply chain risk evaluation. In the process of risk assessment, in order to fully consider the randomness and uncertainty of the evaluation, the fuzzy and random relationship between the risk classification of supply chain and its influencing factors is represented by Cloud model digital language, so as to eliminate the deviation caused by human factors and provide reasonable decision-making basis for supply chain risk assessment.
The structure of this paper is as follows. Section 2 focuses on literature review. Section 3 highlights framework development and research design for concerned studies. Research methodology is discussed in Section 4. Results and outcomes are described in Section 5. Discussions and findings are presented in Section 6. The final section presents conclusions and further research.
Literature review
Supply chain management
In the context of production globalization and knowledge economy, market competition has become increasingly fierce [9]. The increasing of production levels has promoted consumer purchasing and demand diversification [10]. In order to gain consumer recognition in new market environment, enterprises began to change their management thinking from pursuing interests of individual companies to form new types of cooperative relationship [11]. Thus, collaborative relationship between the upstream and downstream are given fully consideration in supply chain management.
In this circumstance, supply chain management faces new problems and risks. Christopher and Lee [12] pointed out that supply chain management is facing four serious challenges: new competition rules, industrial globalization, downward price pressure and strengthen customer control. The challenges along with the complex internal and external environment have caused difficulties in supply chain management. How to effectively identify and evaluate supply chain risks using various technologies is a topic facing both academic and business communities.
Supply chain risk management
At present, more and more scholars and managers have paid enough attention to supply chain risk management. However, an approbatory definition of supply chain risk management has not been formed. Christopher and Towill [13] define supply chain risk management as supply chain members jointly manage external risks through a collaborative mechanism to reduce the vulnerability of the whole supply chain. Juttner et al. [14] believes that identifying potential risk factors and taking corrective measures to control vulnerability is the purpose of supply chain risk management. Sodhi et al. [15] defines supply chain risk management as the coordination and collaboration risk management of supply chain members to ensure the overall benefits and continuity of supply chain. Although there is no consensus definition of supply chain risk management, there are many relatively research results on supply chain risk management.
Supply chain risk is unplanned and unexpected abnormalities that affect the coordination and collaboration of supply chain [16], and may even cause supply chain disruptions [17]. Supply chain risk management is a collaborative process to identify potential risk factors and mitigate the negative impact of risk through various technologies and methods [18]. At the same time, a systematic theoretical framework plays a vital role in guiding supply chain risk management. Analyzing and studying the relationship between these steps is of great significance for understanding the connotation of supply chain risk management.
Supply chain risk identification
Supply chain risk management focuses on risk identification, risk assessment and risk control [19]. Risk identification is the first step in supply chain risk management, and it refers to systematically understanding various risks and analyzing potential causes of risk events. Risk identification can help to establish an effective indicator system so that risk assessment can proceed smoothly. Table 1 shows summary of supply chain risk indicators by different authors.
Summary of supply chain risk indicators
Summary of supply chain risk indicators
Risk assessment is the most important component of supply chain risk management. Supply chain risk assessment not only evaluates the risk issues within the core of supply chain but also evaluates the risks arising from other links in supply chain network. At present, a commonly used risk assessment method for scholars is to make a grade judgment of supply chain total risk level.
Previous studies have focused on methodologies to identify risk indicators and evaluate supply chain risks. Some of these studies on supply chain risk assessment are summarized in Table 2.
Summary of supply chain risk assessment model
Summary of supply chain risk assessment model
As noted, a research gap exists in supply chain risk evaluation models.
When FEMA method is used to evaluate supply chain risks, it first needs to set a certain score range for each risk indicator, and then calculate total score. This method is relatively easy to use but its evaluation is not strong for in fact risk indicators have a certain degree of each other.
The determination of weight is highly subjective when TOPSIS is used to evaluate supply chain risks, and the “best point” and the “worst point” are not easy to determine, so the distance of evaluation goals between “the best advantage” and “the worst point” cannot be determined.
The uncertainty and ambiguity of subjective cognition of experts by AHP-Fuzzy comprehensive evaluation are not convincing. In addition, there are problems such as large data statistics, difficult weight determination and complicated solution of eigenvectors when a large amount of risk indicators is existed in AHP-Fuzzy.
ANN evaluation results are single, and the number of network layers, the number of neuron nodes in each layer, the transfer function and selection of training algorithm are all based on a large number of experimental calculations without feasibility theoretical guidance.
The concept of “curve similarity” in GA (Grey Relational Analysis) theory is not clear. Some calculation formulas lack science and cannot meet the order-preserving effect when the original data is dimensionless.
The demand for SEM samples is large and calculation process is complicated. In actual application, there are existed selected principal components which are not representative of original variables, and the evaluation would be biased. Selected risk indicators are limited when DEMATE is used to evaluate supply chain risks. In fact, the number of supply chain risk indicators is very large and whether the selected risk indicators are representative is an issue to be considered. In addition, when scoring is based solely on subjective assumptions of experts, the obtained scoring results may not be objective and accurate.
Cloud model can simulate human mind to flexibly divide attribute space and complete conversion from quantitative values to qualitative concepts [49]. Also there is an overlapping between adjacent attribute values or languages, which makes the discovered knowledge robust [50]. Moreover, Cloud model can handle data with randomness and uncertainty well, so Cloud model can be introduced into supply chain risk evaluation [51]. Cloud model not only can reduce the impact of subjective indicators on supply chain risk evaluation results, but also realize uncertainty conversion between qualitative concepts and quantitative values to improve accuracy of evaluation results.
On the basis of previous research work, this paper applies cloud model theory to supply chain risk assessment. Based on the existing research results and literature, this paper selects representative and quantifiable factors that affect supply chain risk. Aiming at the problems of high redundancy and complex evaluation process of traditional supply chain risk evaluation indicators, the evaluation index set is reduced by theoretical exploration and empirical screening, and redundant indicators are eliminated to simplify the risk evaluation process.
Research framework and research design
In this section, research framework and research design put forward in this research were described.
Research framework
The detailed research framework of this study is shown in Fig. 1.

Framework of study.
Theoretical exploring initial supply chain risk indicators
(1) Data collection
Theoretical exploring involves database selection, keyword selection and search, title and abstract review, and applying the inclusion and exclusion criteria. A single database is insufficient to retrieve all the references needed for supply chain risk indicators and this might lead to selection bias. In this study, Science Direct (SD), ProQuest (PQ) and Google Scholar (GS) databases are used to enhance the theoretical exploring. SD database has high-quality articles that are published in peer-reviewed journals indexed in SCIE, E-SCI and SSCI. PQ database is included as it is a multidisciplinary database with over 160 subject areas. To ensure a robust analysis without publication bias, GS is used to retrieve the grey literature. The search strings is “supply chain risk indicators” and Table 3 is the inclusion and exclusion criteria for selected articles.
Inclusion and exclusion criteria for 258 selected articles
Inclusion and exclusion criteria for 258 selected articles
Figure 2 illustrates the flowchart of theoretical exploring followed in this study.

Flowchart of theoretical exploring.
To obtain the research focus of each cluster and to label them, the contents such as title, abstract, author keywords in each article are assessed using VOSViewer. VOSViewer is a tool for providing text mining capabilities for building and visualizing co-occurrence networks of important terms extracted from scientific literature. Figure 3 shows the keyword co-occurrence network structure.

Keyword co-occurrence analysis of central cluster “supply chain risk indicators”.
(2) Word frequency statistics
Word frequency statistics is a literature measurement method that takes frequency of words as research object. It uses frequency statistical analysis of keywords to reveal core content and reflect evolution of research field. The content of supply chain risk indicators is broad and has close relations with sociology, economics and other disciplines. But some of them were not highly correlated with supply chain risk indicators, and some are overlapped with each other. We standardized keywords through manual screening and removed keywords that were not very professional and too broad meanings such as “Management”, “Indicator”, “Risk”, etc. Then synonymous and similar keywords were merged such as “Supply risk” and “Management risk” into “Supply management risk”, “Supply risk indicators” and “Risk indicators” into” Supply risk indicators “.
A total of 236 articles were retrieved and 35 keywords with the highest frequency of supply chain risk indicators were obtained, which is shown in Table 4.
Word frequency statistics of risk indicators (F means Frequency)
(3) Brainstorming
Practical experience shows that brainstorming can eliminate compromise solution and find a group of feasible solutions through objective and continuous analysis of the discussed problems. Therefore, brainstorming has been widely used in decision-making. The results of brainstorming should be considered as the collective creation and the overall effect of all experts.
The brainstorming rules should be obeyed as follows:
Criticism and comments are prohibited, and ideas put forward by others must not be criticized or blocked;
The participants are fully relaxed and motivated by the assumptions of others, and fully focused on developing their own ideas;
Free speech is advocated, and the goal of the meeting is to seek for an increasing number of pursuit ideas;
Each participant should inspire or supplement himself with the ideas of others, or combine several ideas of others to come up with new ideas. All participants were equal and all ideas were written down.
Our brainstorming sessions are based on the following facts: invited members are new to this type of meeting; any other type of meeting might prevent some members from participating; members think on their own and the final group discussion will take place. At the beginning of brainstorming, the moderator briefly introduces the issues to be discussed, especially the rules of brainstorming. The brainstorming session lasted two and a half hours, with half an hour break in between so that participants could exchange ideas.
The expertise of brainstorming expert should be consistent with the decision making issues involved and include experts in the field of expertise, senior experts in other areas of expertise and experts with high logical thinking skills. Therefore, the result of the brainstorming is the collective creation of expert members and overall effect of the group’s mutual infection. In this paper, we design brainstorming in different fields, different disciplines and different levels of experts. So we invited university professors, graduate students, undergraduates and government officials to attend the meeting. A total of 11 people attended the seminar, including one moderator. Professional fields range from e-commerce, risk management, economics to ecological management research and other subjects.
In the process of brainstorming, there are usually many experts with different backgrounds proposing ideas, and the moderator is responsible for collecting the similar ideas to form corresponding groups. First, experts with different backgrounds put forward their own ideas. Then, several groups were formed. Each group selected a core expert as the team leader to fully discuss the proposed ideas. Finally, following the rules of brainstorming, new ideas by discussing previous ideas in or between groups are generated. After several rounds of discussion, a perfect solution finally emerged.
The one-factor variance analysis and T-test were performed on the experts’ variables of the gender, education background and degree participated in brainstorming, and the results showed that there were no significant differences in gender, education background and degree of the tested experts, as is shown in Table 5. The statistical analysis also verified that the results of brainstorming are credible.
Respondents characteristics of 11 brainstorming experts
Keywords with a frequency of less than 3 were selected and made judgments using brainstorming and a set of 10 important supply chain risk indicators was finalized, which was presented in Table 6.
Brainstorming results of risk indicators
Note: Please provide your opinion based on given scale S: (save) or D: (delete).
Finally, risk indicators conducted by brainstorming were added to word frequency statistics and initial supply chain risk indicators were constructed (Table 7).
Initial risk indicators of supply chain by theoretical exploring
(1) Measurement grouping variables and instruments
Independent grouping variables are respondents’ genders, age, employment status, education, hierarchical level, expertise, treated for risk management, risk awareness.
The professional and technical expertise of respondent is an important variable because decisions will be formed in relative knowledge and expertise of respondent. The education level influences supply chain risk management in terms of uncertainty related to risk indicators identification and risk control. An efficient treatment for risk management and risk awareness can effectively reduce supply chain risk and it is a very important variable. The hierarchical level can modify the risk indicators and thus the risk’s management. The respondent’s age and employment status also influence their judgement towards supply chain risk.
The characteristics of respondents can affect risk characteristics (risk identification and number of risk indicators) and risk management (risk evaluation, risk rank and risk prevention) of supply chain.
(2) Statistical analysis of data
The first step was a confirmatory study with 500 different questionnaires which were organized between December 2019 and March 2020. The questionnaires were conducted by anonymous questionnaire and were electronically forwarded to respondents. The questionnaire is composed of three parts: characteristics of respondents (genders, age, employment status, education, hierarchical level, expertise, treated for risk management, risk awareness), risk indicators constructed by initial theoretical exploratory, general questions about respondent institution. The major factors in the questionnaires are risk indicators of supply chain by theoretical exploring (Table 7).
Data collection and descriptive statistical analysis such as average values and deviations of respondents’ questionnaires were analysed by SPSS 23.0. The accuracy of respondents’ questionnaires is examined by different statistical analysis: Pearson correlation, multiple linear regression analysis and discriminate analysis.
(3) Sample Characteristics
In total, 467 questionnaires were collected and 448 questionnaires were effectively recovered. The recovery rate of the questionnaire was 93.20% and the effective response rate was 96.14%. The research sample is non-random and appropriate. Therefore, it can be estimated that questionnaires represent the characteristics of the entire respondents. The respondents’ characteristics of 448 questionnaires are shown in Table 8.
Respondents characteristics of 448 questionnaires
Respondents characteristics of 448 questionnaires
(4) Reliability and validity analysis
According to statistical results of questionnaire survey, a reliability test was performed using SPSS 22.0. The reliability of scale is usually expressed by α reliability coefficient. For a high-reliability questionnaire, the reliability coefficient is greater than 0.8. In this paper, the reliability coefficient is 0.9151, which meets the reliability test requirements and proves the stability of the questionnaire (Table 9).
Reliability analysis
Measurement validity refers to it that whether measured characteristic is target to be measured. The questionnaire in this study as created after extensive reading of relevant literature and field research. In the process of data collection, survey subjects were strictly selected. The preliminary statistical inferences of data also indicate that the measurement is valid.
(5) Membership analysis
The threshold value of membership analysis was conducted based on actual experience of 11 brainstorming experts. After comprehensive expert opinions, the threshold value determined by membership analysis was 0.4. Indicators which membership degree is greater than 0.4 (including 0.4) were retained (Table 10).
Membership analysis
M = membership degree.
(6) Correlation analysis
Correlation coefficient is Pearson correlation coefficient. The correlation analysis of survey data showed that there were significant correlations among five pairs of indicators (Table 11). According to the result of correlation analysis, five indicators with high correlation coefficient were eliminated.
Correlation analysis
A total of 12 indicators were finalized risk indicators of supply chain, which is shown in Table 12.
Final supply chain risk indicators
Final supply chain risk indicators
The supply chain risk indicator system is composed of three sub-system aspects: operation, environment and technology. Operation risk mainly includes financial risk, cooperative risk, logistics risk, information risk and resource risk. Financial risk determines the sustainability and robustness of supply chain, and supply chain with capital risk has a certain risk of disruption. The cooperative risk in supply chain is if there is deviation of each other’s values, it is easy to lead to the disintegration of supply chain. Logistics risk such as time delay and efficiency reduction will lose the trust of downstream enterprises in supply chain, which leads to hindered cooperation. Information risk in supply chain mainly refers to supply chain decision-making mistakes which may be caused by the inaccuracy of information and the failure to reach the receiver in time.
Environment risk mainly includes natural risk, policy risk, market risk, sales risk and risk awareness. Natural risk affects every node of supply chain, thus affecting the stability of the whole supply chain. Policy risk not only affects the production and operation of upstream and downstream enterprises of supply chain, but also affects the stability and sustainability of supply chain. Market risk is the risk brought by price, supply and demand change of supply chain products or services, and the risk brought by the sufficiency, stability and price change of raw materials, spare parts and other supplies. Sales risk refers to the impact of price reduction, inventory, seasonal change and consumption habit on supply chain products due to the change of supply chain competitive environment. Risk awareness refers to whether supply chain can respond quickly and what strategies can be adopted to reduce the potential risks.
Technology risk includes security risk and maintenance risk. Security risk can affect the source product of supply chain processing, transportation and later tracing information, as well as processing information, transportation information, storage information, sales feedback information and other information transmission timeliness. Supply chain network needs to achieve information sharing, the higher the degree of sharing, the more the decision-making direction of supply chain is in line with the market demand, this is the maintenance risk.
Cloud model
Cloud is a transformation model that uses linguistic values to represent the uncertainty between qualitative concepts and quantitative concepts in order to achieve the ambiguity and randomness of things in natural world [52, 53]. Cloud not only explains things from random theory and fuzzy theory, but also reflects the correlation between ambiguity and randomness, which constitutes a mapping between quantitative and qualitative [54].
Suppose U is a qualitative concept that contains precise numerical values, C represents the qualitative concept of U. If x ∈ U and x is a random realization of quantitative value C, μ (x) ∈ [0, 1] has a stable tendency to randomness. If:
Then, the distribution of x in quantitative field U is called a cloud, and each x is called a Cloud drop.
The digital characteristics of cloud are reflected the integrity concept of Cloud based on normal distribution function and normal membership function. Three digital features Ex (Expected value), En (Entropy) and He (Hyper entropy) are represented the concept of Cloud. Ex: In the universe space, Cloud drop is the point that can best represent the qualitative concept, and its expectation is the centre value in the universe space. En: En is jointly determined by randomness and ambiguity of qualitative concept and reflects the degree of dispersion of Cloud drop [54]. It also reflects the value range of cloud drops that can be accepted by qualitative concepts in the universe of space. The larger the value ranges of cloud drops, the more fuzzy the qualitative concepts, which also reflects the correlation between randomness and ambiguity. He: He is the uncertainty measure of En. It reveals the cohesion, uncertainty and ambiguity of all points in linguistic value.
Forward cloud generator
The evaluation interval [αβ] of the comment object is divided into n sub-intervals, where the i sub-interval is
η is a constant that reflects the randomness of the evaluation value. The value of η should not be too large because He i becomes larger, Ex i needs to be adjusted according to the degree of ambiguity of the comment itself (Fig. 4).

Forward cloud generator.
The determination of cloud parameters is based on inverse cloud generator model. The purpose of reverse cloud generator is to generate three characteristics Ex, En and He of Cloud model. Enter sample points X i = (xi1, xi2, ⋯ , x im ), i = 1, 2, ⋯ , n and m characteristics (Ex1, Ex2, ⋯ , Ex m ; En1, En2, ⋯ , En m ; He1, He2, ⋯ , He m ) of cloud (C1, C2, ⋯ , C m ) are output (Fig. 5).

Reverse cloud generator.
The process is as follows:
(1) Membership calculation
(2) Ex i calculation
(3) En i calculation
(4) He i calculation
Cloud computing rules are shown in Table 13.
Cloud computing rules
Cloud computing rules
Cloud evaluation of supply chain risk is described as follows: Define risk factors and evaluation criteria, then establishing factor sets and review sets. Determine weight sets and obtaining the relative weights of different risk factors. Generate comprehensive evaluations in the form of digital features of Cloud models by reverse cloud generator and weight coefficient matrix.
In the fuzzy Cloud comprehensive evaluation method, Cloud model is used to calculate weight coefficient matrix and comprehensive evaluation matrix without traditional membership function. First, distribution of weights is statistically analyzed, and then, the parameters (Ex1, Ex2, ⋯ , Ex
m
) are derived using the inverse Cloud generator model. Thus, the obtained weight coefficient matrix is:
For comprehensive evaluation matrix, the risk scores are assigned to corresponding risk scales, and then, the statistical samples are converted into parameters (Ex1, Ex2, ⋯ , Ex
m
) using inverse cloud generator. The comprehensive evaluation matrix is:
(4) Comprehensive evaluation of Cloud models of risk factors
The fuzzy Cloud comprehensive evaluation results are obtained from the above formulas, and the hierarchical and stability characteristics are analyzed. Generally, the following priority relationship can be used for sorting:
Ex should be compared first, the bigger Ex is, the better the ranking;
If Ex are the same, the smaller En is, the better ranking;
If Ex and En are the same, the smaller He is, the better ranking.
Establishing linguistic and weight set of risk indicators
Nine linguistic rating scales is used to deal the uncertainty of human’s subjective judgments and the linguistic matrix of risk indicators is developed with the help of experts’ judgments [55]. Linguistic set of risk indicators are defined: extremely low = L0, fairly low = L1, very low = L2, low = L3, medium = L4, high = L5, very high = L6, fairly high = L7, extremely high = L8. The results of linguistic set are shown in Table 14.
Linguistic set of risk indicators
Linguistic set of risk indicators
Weight comparison matrix is established using the five rating scales and the specific meanings and codes are defined: extremely unimportant = C0, unimportant = C1, medium = C2, important = C3, extremely important = C4.
Seven business personals who were familiar with the business management process and expert in risk assessment were invited to evaluate risk indictors using different linguistic set. The results of weight set are shown in Table 15.
Weight set of risk indicators
In this step, the linguistic set and weight set of risk indicators are calculated to acquire Cloud matrix, which is shown in Table 16.
Weight cloud matrix and linguistic cloud matrix
Weight cloud matrix and linguistic cloud matrix
The weight Cloud matrix and linguistic Cloud matrix of risk factors are represented by matrices A and R. Therefore, the final evaluation of supply chain risk Cloud matrix result is as follows:
Cloud model comprehensive evaluation results
The risk intervals are divided into five categories: extremely low risk, low risk, medium risk, high risk, and very high risk. The Cloud parameters for each risk interval are shown in Table 17.
Risk interval and standard cloud parameter
Risk interval and standard cloud parameter
Figure 6 shows Cloud evaluation results of supply chain risk compared with standard cloud parameters.

Evaluation result of supply chain risk.
It is clear that Cloud model evaluation results is between general risk and high risk but closer to high risk, the evaluation results are more strongly affected by high-risk cloud model. Therefore, risk level of supply chain is high risk. In addition, Cloud expected value of risk is 6.5400 which is within the high-risk range of [6, 8], and evaluation results are also high risk.
Evaluation result comparison
In order to verify the reliability of Cloud model for supply chain risk assessment, this paper evaluates the factors and weights selected in Cloud model with the fuzzy comprehensive evaluation method, using conventional fuzzy comprehensive method, the linguistic set and weight set are also used to calculate the data in Cloud model, and the final evaluation result is:
According to the risk factor evaluation form, the supply chain has a medium risk. The risk weight of Cloud evaluation model compared with conventional fuzzy comprehensive evaluation is shown in Table 18.
Risk weight and rank comparison
Risk weight and rank comparison
The most important risk indicator is known to be risk awareness (RF10) and natural risk (RF6) which is found to be the least important one. Hence, risk awareness should be given the top priority in supply chain risk management. Moreover, Fuzzy comprehensive evaluation methods fail to effectively rank risk indicators in supply chains. Because risk evaluation is needed to be able to identify risk indicators, risk identification is the key step of supply chain risk management. Cloud model not only evaluates risk but also rank risks in supply chain.
The evaluation results are consistent with the Cloud model evaluation results. The results show that the model is feasible and effective, and the model considers the disturbance factors of supply chain risk indicators, which is closer to the actual situation.
Supply chain risk is a qualitative concept, which is difficult to be measured by conventional mathematical model. However, Cloud model can quantitatively express the qualitative classification of supply chain risk with Cloud digital features. The positive normal cloud generator of Cloud model can represent the randomness and fuzziness of supply chain risk classification by quantitative value of certainty calculation, and can better reflect the conversion relationship between qualitative language and quantitative value uncertainty in the process of supply chain risk level evaluation. Besides, its application is reflected on the risk evaluation in this paper.
(1) Cloud evaluation has better flexibility and ranking priority
Fuzzy comprehensive evaluation cannot determine the priority order of factor weights when weights are the same, so the similarities and differences between the two cannot be explained (Fig. 7). Therefore, in actual evaluation, there are ambiguity and randomness from the selection of evaluation domain in the calculation of weight coefficient and the generation of comprehensive evaluation matrix. Cloud model not only ranks the evaluation results but also analyzes the inherent uncertainty of evaluation objects, thus providing richer reference information for risk assessment.

Rank of supply chain risk indicators.
(2) Cloud valuation has better randomness and robustness
Results obtained by conventional Fuzzy evaluation method are not reflected in the volatility and randomness. Moreover, in order to compare the simple results, the final evaluation result is simplified into a conversion score, which does not reflect the vague essence (Fig. 8).

Fluctuation of supply chain risk indicators.
It can be seen from the evaluation results that Cloud evaluation model is consistent with evaluation results of existing methods, which shows that Cloud comprehensive evaluation method is reasonable and feasible. Moreover, Cloud fuzzy comprehensive evaluation method has volatility and randomness, reflecting the essence of ambiguity.
In this paper, the Cloud model theory is introduced, and the characteristics and advantages of the transformation between qualitative language and quantitative value are applied to the evaluation method of supply chain risk level. The Cloud model of supply chain risk level evaluation can not only realize the uncertain mapping between the value of supply chain risk factor and the qualitative description of supply chain risk level category, but also can convert supply chain qualitative risk level to corresponding Cloud model levels. This model has two advantages: The model is to make full use of the uncertainty transformation mechanism of Cloud model, which makes the evaluation system take into account both subjectivity and objectivity, and has better flexibility compared with the traditional supply chain risk evaluation model. The supply chain risk rating evaluation model based on cloud model realizes the transformation between the supply chain risk level category and the supply chain risk factor value, and to a certain extent, modifies the influence of subjective factors in the evaluation and the subjectivity of the evaluation results. In addition, it further explores the main influencing factors of the evaluation results, so as to make the comprehensive evaluation results objective and reliable, which is conducive to the follow-up optimization and avoidance of risks. Compared with Fuzzy mathematics, Cloud model can consider both fuzziness and randomness.
However, the algorithm of reverse Cloud generator is based on statistical principle, and approximately deduces the overall characteristics with the characteristics of samples. There are some errors in this process, which need to be studied and improved by later scholars. Besides, This paper gives a theoretical evaluation method of supply chain risk based on Cloud model. Although it has been verified by empirical research, the basis of index system construction is still not complete. It is expected that later scholars’ research can improve the basis of index system construction.
Footnotes
Acknowledgments
This work was financially supported by Social Science Foundation of Shandong Province (Grant No. 19BJCJ20).
