## 2 Literature Review
### Background of the Research Related to the Proposed Method  
The evaluation of PPE performance involves the assessment of a variety of factors. The factors are identified as the criteria, which have different levels of importance. Unlike a traditional criteria evaluation, the factors may interact with each other, and the relationships among them need to be considered. Therefore, the evaluation problem of PPE performance can be regarded as a multi-criteria decision-making problem. In previous research on patterns of construction fall accidents, most research focused on the identification and prioritization of influential factors that cause fall accidents and injuries. For example, [PERSON] et al. [20] investigated the major factors of fall accidents in the U.S. construction industry from 2000 to 2020 and analyzed the data through frequency analysis and correlation analysis. [PERSON] et al. [21] identified sixty-two key factors influencing safety performance in high-rise building projects in Malaysia and highlighted the most critical factors based on the questionnaire survey. [PERSON] et al. [22] proposed a model to predict the factors that caused fall accidents through machine learning for Malaysian construction projects. On the other hand, the interrelationships among the identified criteria affecting construction fall accidents have rarely been taken into account in past studies. In order to incorporate the inter-correlated criteria, the multi-criteria decision-making (MCDM) method, which identifies the optimal solution from multiple choices, is an effective method for accident analysis [23]. Different researchers have focused on the systematic assessment of complex decision-making problems regarding construction safety management. For a comprehensive analysis of structuring accidents, a model combining the decision-making trial and evaluation laboratory (DEMATEL) technique and the analytic network process (ANP) method utilized the judgment and feedback of experts to determine the relationship among the factors and prioritize the alternative solutions [24]. [PERSON] et al. [25] developed a model to select suitable PPE for a given workplace based on AHP, which was effective in determining the dominant criteria and critical factors in a PPE evaluation and ergonomic assessment. [PERSON] et al. [26] proposed a decision-making method that integrated the ANP method and DEMATEL to rank the factors influencing construction fall accidents. Based on the relationships between various factors, this research used the ANP method to calculate the corresponding weights. Through ANP and DEMATEL methods, the construction contractor selection models were developed to determine the contractor from a safety perspective and analyze different criteria, such as the safety risk, quality, and cost, to select the best contractor alternative [27; 28]. Based on hybrid AHP and VIKOR methods in a fuzzy environment, [PERSON] et al. [29] established a risk assessment model to evaluate the risk level of workers' health and safety. This research identified the most critical factors, such as the environment, PPE, and safety training, and further determined the compromise solution as the \"melting furnace\". Furthermore, the decision-making process is always challenged due to a lack of experience and limited information about potential alternatives. Therefore, VIKOR is an effective method to select the alternative that is closest to the ideal solution. Meanwhile, considering that there is much ambiguous and uncertain information in the decision-making process, fuzzy theory is widely used to capture the fuzzy information in the decision-making process of the respondents and is capable of transforming the vague information into computable and accurate numbers. The VIKOR method, developed by [PERSON] and [PERSON] (2004), can be applied to solve MCDM problems. As VIKOR is effective in dealing with conflicting criteria, it ranks the potential alternatives and selects the ideal solution.