Unveiling the Dynamics of Consumer Attention: A Two-Stage Hybrid MCDM Analysis of Key Factors and Interrelationships in Influencer Marketing

: In recent years, influencer marketing has taken over traditional brand advertisements on social media platforms, combining word-of-mouth marketing with celebrity endorsements. However, there has been limited academic research on the key success factors in influencer marketing. This paper used a hybrid MCDM model that integrates the Delphi method and the decision-making trial and evaluation laboratory (DEMATEL) approach. Through a two-stage empirical study, the research aims to explore the crucial success factors in influencer marketing. This study focuses on the Taiwanese market. The target respondents for the survey are consumers in Taiwan who have purchased products or services based on recommendations from key opinion leaders (KOLs) or internet celebrities. This systematic research framework not only pinpoints key factors that capture consumer attention towards influencers, but it also illustrates the inter-relationship of structure and improvement directions among these factors. According to results, the key factors include influ-encer reputation, credibility, degree of key opinion influence, attractiveness, popularity, consistency between influencers and brands, fan engagement level, and informativeness. Finally, businesses can consider five aspects to be the purpose of collaboration, product type, target audience for the product, characteristics of the influencer’s creative content, and media attributes. By comprehensively considering these aspects, businesses can determine the appropriate format for collaborative content. This decision can then guide how influencers communicate with consumers, effectively conveying brand information to the relevant target audience. The research findings provide fresh and significant insights in the field of influencer marketing studies.


Introduction
Before the emergence of social media and internet celebrities, professionals in specific fields who easily became key opinion leaders (KOLs) were often exposed through traditional media and physical channels.They were considered experts in certain fields and were respected by their followers for their opinions and professional knowledge [1,2], such as politicians, doctors, entrepreneurs, and writers [3].
KOLs are believed to be experts in a particular field or have extensive experience with a specific topic, and their knowledge is respected by their followers, who consider their advice trustworthy [4].Representing a select group of individuals with expertise in specific areas [5], KOLs, owing to their exceptional education and social status, wield the power to influence consumers and instill trust.This influence has paved the way for the surge in influencer marketing, where companies seek collaborations with influential figures for the promotion of products or services.The rapid rise of the influencer marketing industry recently is evident in the global market, which expanded from $1.7 billion in 2016 to $13.8 billion in 2021 [6].Diversified social media platforms are gradually taking over the roles once held by traditional media.A question arises: How can influencer marketing be effectively employed to sway a target audience and achieve the desired outcome?While previous research has extensively delved into "the influence of influencers on consumers" [7][8][9][10][11], there remains a notable gap in exploring "why consumers are drawn to influencers" from their perspective.This study aims to delve into consumer perspectives on influencer marketing, with a particular focus on the critical factors consumers prioritize in influencer endorsements.Specifically, it seeks to understand how consumers perceive influencers and their reactions to influencer marketing initiatives, thereby identifying pivotal success factors within this burgeoning marketing landscape.Insights gleaned from this research hold immense significance for several reasons.Firstly, understanding consumer attitudes and behavioral responses towards influencers is paramount for businesses striving to succeed in today's competitive market environment.Secondly, the study endeavors to bridge existing research gaps by systematically examining the factors that capture consumer attention towards influencers from the consumer standpoint, thus contributing to a more comprehensive understanding of influencer marketing dynamics.
The literature on endorser effectiveness frequently highlights the viewpoints of marketers regarding the most potent techniques for enhancing the persuasiveness of commercials, particularly emphasizing the focus on endorser characteristics such as message value and source credibility [10], or the product-endorser congruity [12,13].However, ineffective endorsements may occur when the focus is solely on the association between the product and the endorser, rather than considering the connection between the endorser and the consumer [14,15].In the era of influencer marketing, characterized by increased engagement rates and heightened levels of proactivity-such as following brands, visiting their websites, and making purchases following exposure to brands-a notable shift is necessary towards prioritizing consumer-endorser identification and evaluation [14].Importantly, there is a noticeable void due to the absence of a structured assessment framework that thoroughly evaluates the impact of influencers, incorporating consumer perspectives to corroborate insights from brands and marketing experts.This study provides empirical support for the proposed endorser identification model across two studies.In doing so, it directly responds to a recent appeal by [16] for a comprehensive framework to elucidate the diverse range of celebrity endorsements practiced in advertising.Current research extensively explores four key dimensions in understanding consumer attitudes, reactions, and behavioral intentions towards influencers [7,8,[17][18][19][20][21][22][23][24][25][26][27][28].The decision-making trial and evaluation laboratory (DEMATEL) method offers a systematic evaluation framework for marketing research with advantages including structural analysis, visualization, quantitative and qualitative analysis, key factor identification, decision support, and adaptability.It is a powerful tool for analyzing complex relationships and prioritizing key factors in various domains, particularly in marketing contexts, as demonstrated by numerous studies [29][30][31][32][33][34][35][36][37].
This study makes its first contribution by establishing a systematic research framework comprising four dimensions drawn from the relevant literature.Firstly, the focus is on grasping the persuasiveness of influencers, examining their trustworthiness and validating message authenticity [38].Secondly, influencers, who are perceived as more credible, effectively convey brand messages through rich forms of intellectual assets by leveraging creative freedom, fostering crucial relationships and engagement with followers [10,39,40].Thirdly, studies delve into psychological processes, emphasizing emotional connections that satisfy followers' needs and shape beliefs.Lastly, preferences vary across platforms prompting influencers to manage communities on multiple channels.Consumers consider media characteristics and past experiences when selecting channels, influencing their inclination to share information, brand loyalty, and purchase intentions.
This study also contributes to the literature by proposing and employing a two-stage approach.Stage 1 uses Delphi from 11 experts, which comprise 8 marketing experts who have more than 10 years of working experience on average, with the titles marketing director, design director, marketing vice president, senior marketing manager, product manager, and CEO and co-founder of a public relations firm.We also interviewed three influencers who operate on FB and IG with numbers of followers, ranging from 40 k to 110 k, specializing in cosmetics, lifestyle, travel, and delicacies.We have noted the extant literature investigating intentions and attitudes, but limited research has focused on actual purchasing behavior.Additionally, we surveyed 174 consumers who have actual purchasing experience or behavior driven by influencers' endorsement.To the best of our knowledge, we recruited more than 500 consumers and 174 returned (30% response rate); the rest were filtered out because of a lack of actual shopping experience using influencers' recommendations.The third contribution is of practitioners who need an operatable assessment framework when selecting influencers from a large pool across social media platforms.
The primary focus of this study is to apply theoretical methods to practical applications, with the aim of bridging the gap between theory and practice in the realm of influencer marketing.It seeks to thoroughly validate the applicability of research methods in this field while yielding valuable results.Despite the relevant literature addressing the application of theoretical methods, their utilization in influencer marketing research remains relatively limited.Moreover, this study innovatively considers both brand and consumer perspectives, thus contributing to the innovative advancement of influencer marketing research.
The rest of this article is structured in the following manner.In Section 2, we delve into the relevant literature.Section 3 provides a concise explanation of the Delphi and DEMATEL methods' procedures.The analysis and results are showcased in Section 4. Lastly, Section 5 offers our concluding remarks.

Literature Review
Social media has opened new possibilities for marketers and has become the most influential marketing tool, allowing marketers to connect with thousands of target markets without time or geographic limitations [41].The existence of social networks has become an important part of marketing strategies, and promoting products through business accounts online and advertising on social media platforms has been proven effective [42].Therefore, many companies have created official accounts on various social platforms, established communication channels with consumers, and promoted their brands, products, and services through visual and multimedia content to attract consumer attention and engage with them.While the general concept of audience overlap may not be surprising, the extent of these overlaps has particular relevance to marketers.The concept of audience overlap is not surprising, but its extent holds significance for marketers.Brands need not be present on every platform.The data suggest that being active on one or two major platforms can potentially reach nearly all social media users worldwide.Around six platforms have over 1 billion monthly users, and at least 17 have over 300 million users.However, this does not imply that marketers should solely target these large platforms.The data support a strategic, portfolio-based social media approach.Instead of just reach, marketers should explore factors like platform-specific creative opportunities, content formats, and engagement possibilities on more specialized platforms.The illustration in Figure 1 represents the most widely used social platforms globally.
According to Figure 1 [43], among the world's most commonly used social platforms, Taiwan's social media usage has reached 82.6 percent of its population.As illustrated in Figure 2, the top five most frequently utilized social media platforms are Line, Facebook, Instagram, Facebook Messenger, and Tiktok in Taiwan [44].However, while social platforms are inundated with brand advertisements, there i a group of people who share content that can attract attention and trust, commonly known as internet celebrities or social media influencers (SMIs).They use the internet or variou media tools to showcase their charm and unique perspectives, turning their every mov into popular content, even incorporating products or services.

Influencer Marketing
SMIs have become a more common type of internet celebrity, capable of directly in fluencing the thoughts and purchasing decisions of most audiences, and consumers judg them as reliable sources of information.Because they are highly regarded people who  However, while social platforms are inundated with brand advertisements, there is a group of people who share content that can attract attention and trust, commonly known as internet celebrities or social media influencers (SMIs).They use the internet or various media tools to showcase their charm and unique perspectives, turning their every move into popular content, even incorporating products or services.

Influencer Marketing
SMIs have become a more common type of internet celebrity, capable of directly influencing the thoughts and purchasing decisions of most audiences, and consumers judge them as reliable sources of information.Because they are highly regarded people who However, while social platforms are inundated with brand advertisements, there is a group of people who share content that can attract attention and trust, commonly known as internet celebrities or social media influencers (SMIs).They use the internet or various media tools to showcase their charm and unique perspectives, turning their every move into popular content, even incorporating products or services.

Influencer Marketing
SMIs have become a more common type of internet celebrity, capable of directly influencing the thoughts and purchasing decisions of most audiences, and consumers judge them as reliable sources of information.Because they are highly regarded people who participate in and share self-created content through social media, followers usually have a strong attachment and admiration for their lifestyle and behavior [45].
SMIs also specialize in certain areas, such as beauty, fashion, food, travel, or lifestyle, and operate personal brands through social platforms, openly sharing their lives or conveying certain ideas.Therefore, when an internet celebrity is popular on social media and has a large following, consumers may view them as key opinion leaders (KOLs).They may even help disseminate product messages through corporate partnerships, which is a common practice in social media where SMIs share and recommend products to try and change consumer perceptions and behavior towards brands.When influencers recommend products, it seems to be more trustworthy than traditional advertising, making consumers more likely to purchase the recommended products [10,45].For consumers, the most persuasive purchasing behavior comes primarily from recommendations from sources they trust [46].
Influencer marketing is considered a type of word-of-mouth marketing or electronic word-of-mouth (e-WOM) that involves informal recommendations or endorsements of products or services, which include opinions of the brand and evaluations of the strengths and weaknesses of the product or service [47].The most common form of influencer recommendation is similar to recommendations from friends or online product reviews, where messages are spread through word-of-mouth or videos and texts and have the potential to influence consumers' decisions and become a more trusted and commonly adopted opinion.As consumers can freely create and spread brand-related messages through social media, and demonstrate their brand preferences to others through social interactions [48][49][50], they can also influence the thoughts and behaviors of others.The characteristics of social media platforms accelerate the reach of influence, making social media an ideal tool for spreading electronic word-of-mouth.Based on the "Influencer Marketing Trends Report for Asian Countries" by [51], around 88% of brand marketing budgets are allocated to influencer marketing.
This indicates that many companies are gradually realizing the benefits of collaborating with influencers.Companies use social media personalities to reach their target audience, by finding suitable influencers offering them free products or payment to create content and delivering brand-and product-related information to their primary target audience, thereby increasing brand awareness and purchase intent [10,52].This is how influencer marketing is implemented on social media, rendering it a prevalent marketing strategy within the realm of social media marketing.
According to [53], compared to celebrities, consumers are more likely to purchase products recommended by non-celebrities.This phenomenon is more pronounced in the 18 to 34 age group.Many scholars believe that the emergence of influencer marketing is due to the decreasing effectiveness of traditional media communication, and the recognition that user-generated content online is more effective in forming brand preferences and inducing behavioral change than traditional forms [54][55][56].

The Dimensions and Criteria of Influencer Impact Customers
When studying how influencers impact consumer behavior in influencer marketing, the research literature mainly focuses on four aspects to explore consumers' attitudes, reactions, or behavioral intentions towards influencer marketing.First, from the perspective of message dissemination, the persuasiveness of the sender to the receiver is understood, which is to study the characteristics of the influencer and the authenticity of their message for the consumer.Relevant studies have verified that the influencer's impact on the consumer's perception, attitude, and even purchasing behavior during the interactive communication process through social media mainly comes from their trustworthiness because the influencer personally tried the product [38].Although we tend to trust a particular brand when shopping, we still rely on others' opinions when making purchase decisions [57].
Second, influencers convey their ideas or brand-related messages on social media in the form of text, images, and audiovisual content.Among them, the content they provide has become a key element in building a relationship with their fans [39].Some researchers believe that compared to the messages provided by traditional celebrities, the messages provided by social media influencers are more credible, relevant, and authentic [45].In terms of content creation, celebrities usually do not participate in creating content, whereas in influencer marketing, most business owners are less involved in promoting content creation, mainly due to considering consumers' defenses against commercial advertising.Therefore, influencers are given more creative freedom.Although brands often find it difficult to create engaging social media content, influencers are experts in interacting with consumers, which helps content spread more widely on social media [54].Social media influencers can be considered as celebrity-like content creators, whose own image may transfer to the endorsed products and brands [10,40], which also shows the importance of business owners choosing suitable influencers.
The third aspect to explore is the deep psychological processes that occur when consumers face influencers from a psychological perspective.The author of [58] demonstrated that the influence of social media influencers comes from the emotional connections they establish with their followers, satisfying their needs, including the inspiration provided by influencers for their ideals, the relationship between followers and influencers, and the ability demonstrated by influencers through their content.In other words, when consumers believe they share certain interests, values, or characteristics with influencers, they are more likely to adopt their beliefs, attitudes, and behaviors [59].
Finally, regarding research on consumer behavior using social media, there are differences in preferences between different platforms.With the increasing diversity of social media development, people not only use a single social platform but also influencers use two or more social platforms to manage their communities.When companies collaborate with influencers, they do not rely solely on a single channel for influencer marketing.In addition to seeking and exchanging information, interpersonal social relationships are also important factors that enable people to continue using or sharing information in social communities [60,61].Therefore, consumers consider media characteristics and the value generated after use based on their past experiences using social media platforms when choosing different channels to follow influencers.Even when consumers feel a direct interactive relationship with social media operators, it indirectly increases consumers' willingness to share information, brand loyalty, and purchase intentions [62].
Based on the four dimensions we mentioned above, researchers have conducted studies on the assessment criteria within these four constructs.This study has identified 29 assessment criteria, which are described as follows in Table 1.We can divide 29 criteria into four dimensions which are described as follows in Table 2. Influencers' content is believed to convey higher social status and aesthetic taste, receiving high evaluations.17

Visual attractiveness
The degree of visual attractiveness in influencers' content.
18 Informativeness The richness of information in influencers' content, providing diverse content about product/service features and user experiences.

Interactivity
The level of interaction and communication between influencers and their audience in the content.

20
Commercial orientation Consumers' perception of sponsored or commercially driven content.

Product differentiation
When influencers promote products that differ from the standardized designs, consumers may blindly judge the product's ability to meet their needs due to its uniqueness and scarcity in the absence of sufficient information.[9] Influence on consumers' expectations of brand value (A6) [11] Consistency between influencers and brands (A7) [57] Popularity (A8) [63] Influencer reputation (A9) [64] B.

Research Method
The conceptual framework of this study (shown in Figure 3) primarily involves conducting experiments in two main experimental stages after consolidating factors of attracting consumers using influencers through a literature review.The first stage employs the Delphi method using brands or influencers as experts to identify their emphasized aspects and criteria in influencer marketing.According to the literature, the customer-focused approach is a current trend in marketing [14].Hence, this study employs the DEMATEL method to survey consumers who have made purchases based on influencer recommendations.This stage not only helps understand which criteria are the key considerations for consumers with purchasing experiences but also reveals the relationships among these key factors, identifying causes and effects.Based on these results, appropriate influencer marketing strategies can be formulated.

Delphi Method
The Delphi method was developed by RAND in the 1950s to forecast the effect of technology on warfare.It has since been applied to health care, education, management, and environmental science.After reviewing the research of domestic and international scholars, it is evident that previous studies have predominantly emphasized the defined issues.The Delphi method is used to solicit opinions from multiple experts through anonymous written discussions.This approach guides experts to establish a consensus based on their professional knowledge, experience, and thoughts, ultimately addressing complex issues [67].Therefore, this study will use the Delphi method to establish a formal research framework for identifying key factors attracting consumer attention to influencers.
The primary steps of using the Delphi method can be summarized as follows: (1) The Delphi method is used to arrive at a group opinion or decision by surveying a Previous studies have mostly used the research method of hypothesis testing in statistics to validate and discover that various factors directly or indirectly influence consumers' attitudes towards brands, influencers, and purchase decisions.These factors can be considered as influencing factors that affect consumers' attention to influencers.The DEMATEL method helps understand its characteristic of evaluating the complex relationships behind quantitative analysis problems.By using matrices and mathematical theories, it determines the causal relationships between all factors and observes the impact between each pair of factors.It expresses the strength of the influence and causal relationships between criteria using network relationship diagrams, in order to identify the core issues and improvement strategies for complex issues.
This study will employ the DEMATEL method to clarify the causal relationships between dimensions and criteria.DEMATEL not only provides a method for solving complex problems but also enhances understanding of specific issues and offers decisionmaking solutions using existing hierarchical structures.By analyzing the relationships and direct influence matrix among the elements in the system, the method can calculate the degree of influence and be influenced by each element.This approach has been widely used to address various complex research problems [65].

Delphi Method
The Delphi method was developed by RAND in the 1950s to forecast the effect of technology on warfare.It has since been applied to health care, education, management, and environmental science.After reviewing the research of domestic and international scholars, it is evident that previous studies have predominantly emphasized the defined issues.The Delphi method is used to solicit opinions from multiple experts through anonymous written discussions.This approach guides experts to establish a consensus based on their professional knowledge, experience, and thoughts, ultimately addressing complex issues [67].Therefore, this study will use the Delphi method to establish a formal research framework for identifying key factors attracting consumer attention to influencers.
The primary steps of using the Delphi method can be summarized as follows: (1) The Delphi method is used to arrive at a group opinion or decision by surveying a panel of experts.In this study, the Delphi method is employed to investigate how brands or influencers, acting as experts, identify their emphasized aspects and criteria in influencer marketing.
The Delphi method effectively increases the proportion of items that reach consensus after multiple rounds.The main objective of the first round is to collect initial opinions from experts as a basis for the design of the subsequent questionnaire.Experts are asked to review whether the definitions of constructs and criteria in the prototype research framework are clear and to confirm the completeness of the research framework in this round.Based on the feedback from the first round, the second round designs a rating questionnaire and sends it to experts for the first round of rating.Each expert rates whether each criterion needs to be included in the research framework.The entire process ends when consensus arrives on all criteria; otherwise, experts must continue with the following rating round.This study will use Quartile Deviation (QD) to check for agreement.QD is half of the interquartile range (IQR), and the interquartile content is the distance between the 25th percentile (or the first quartile Q1) and the 75th percentile (or the third quartile Q3) of all data sorted from smallest to largest.Because nearly 50% of the data are between Q1 and Q3, IQR is less affected by extreme values.Overall, when the quartile deviation is ≤2, a consensus can be considered achieved [68]; in the third round, based on the rating results of the second round, the questionnaire is redesigned, and the questionnaire is sent back to each expert for the second round of rating.Although each expert must rate each criterion again, the expert must explain if the new rating falls outside the quartile range.Like the second round of questionnaires, the Delphi process ends when consensus arrives at all criteria.

DEMATEL Method
There is a causal relationship between the factors explored in this study, which examines how consumers perceive influencers and what key factors they value most in influencer marketing from the consumer's perspective.The dependence among factors is conducive to further developing source management strategies.A characteristic of the DEMATEL method is to analyze the key factors and causal relationships among factors effectively [69].This study used DEMATEL to clarify the dependence among factors influencing the purchase intention of electric vehicles.In the past, scholars have employed the DEMATEL research method to consider the combination of scales and semantics, often designed on a rating scale of 0 to 5 [69].In order to facilitate respondents' ease of completion, this study adopts a three-point scale approach, following the method of [70,71].It uses a scale of 0, 1, and 2 to identify the degree of mutual influence between factors: 0 represents no influence at all, 1 represents slight influence, and 2 represents significant influence.The DEMATEL calculation process can be summarized into several steps.Please refer to references [70,71] for the detailed calculation process of the DEMATEL method.

The Relevance of Dimension and Criterion
After establishing the research prototype framework through a literature review, this study followed the Delphi Method to establish the formal research framework.A panel of 11 experts was selected for this study, including 8 experts who are senior executives in brand or influencer marketing and 3 experts who are influencers themselves.All selected experts are professionals in the field of influencer marketing.They were invited to participate in revising the questionnaire framework to provide comprehensive professional insights.
After the first round of expert interview questionnaires, the revised prototype framework was obtained, comprising four dimensions and 26 criteria.Subsequently, based on the necessity assessment results from the second round of the expert panel, all 26 assessment criteria had an interquartile range (IQR) value of ≤2.This indicates that the expert panel had achieved a consensus regarding the necessity of incorporating the assessment criteria into the research framework.Following discussions with the expert panel, it was agreed upon that a threshold of an average score of 4.28 would be used to determine the deletion of assessment criteria.This means that criteria with an average score lower than 4.28 would be considered less necessary and could be removed.Therefore, after expert confirmation, the formal research framework of this study consists of four dimensions and 14 criteria.
This study distributed a total of 500 questionnaires of which 174 valid responses were collected in Taiwan.Valid responses were defined as those from consumers who genuinely made purchases due to influencer recommendations.The characteristics of the sample are outlined in Table 3.In terms of gender, the majority of those who made purchases due to influencer recommendations were female.Regarding age, individuals aged 21 to 30 and 31 to 39 were the most interested in influencers.However, among the 174 respondents, a higher percentage commonly use social media platforms such as YouTube (80%), Facebook (76%), and Instagram (74%) to follow and track influencers' lives, while a minority use platforms like Twitter and blogs to follow influencers, as illustrated in Figure 4.It was found that 147 individuals (84.5%) use two or more social media platforms to follow influencers, indicating that consumers' media usage habits mostly involve using multiple social media platforms to follow different influencers.For the direct influence matrix, a total of 174 valid questionnaires were collected in this study.The values in the same column of each questionnaire were summed and averaged to obtain the direct influence matrix (Z) as shown in Table 4.The sums of each column and each row of the direct influence matrix (Z) were calculated.The maximum value among the sums was used in the calculation formula of the DEMATEL method to obtain the normalized direct influence matrix (X) as shown in Table 5.The normalized direct influence matrix (X) was used in the calculation formula of the DEMATEL method to obtain the total influence matrix (T) as shown in Table 6.The values of each column in the total influence matrix (T) were summed to obtain the column sum (D), and the values of each row were summed to obtain the row sum (R).The results of importance (D + R), relation (D − R), and the ranking of importance are shown in Table 7 for each dimension.The causal diagram among key dimensions, as shown in Figure 5, is illustrated.The normalized direct influence matrix (X) was used in the calculation formula of the DEMATEL method to obtain the total influence matrix (T) as shown in Table 6.The values of each column in the total influence matrix (T) were summed to obtain the column sum (D), and the values of each row were summed to obtain the row sum (R).The results of importance (D + R), relation (D − R), and the ranking of importance are shown in Table 7 for each dimension.The causal diagram among key dimensions, as shown in Figure 5, is illustrated.

Drawing Causal Diagram and Generating the Total Influence Matrix
According to Table 7, the main dimensions influencing "B.Content Characteristics" and "D.Platform Selection" are "C.Consumer Psychological Factors".The main dimension influencing "C.Consumer Psychological Factors" is "A.Influencer Characteristics".
In this study, a total of 174 valid questionnaires were collected.The values in the same column of each questionnaire were summed and averaged to obtain the direct influence matrix (Z).Based on the calculation according to [70,71], we can finally obtain the required

Drawing Causal Diagram and Generating the Total Influence Matrix
According to Table 7, the main dimensions influencing "B.Content Characteristics" and "D.Platform Selection" are "C.Consumer Psychological Factors".The main dimension influencing "C.Consumer Psychological Factors" is "A.Influencer Characteristics".
In this study, a total of 174 valid questionnaires were collected.The values in the same column of each questionnaire were summed and averaged to obtain the direct influence matrix (Z).Based on the calculation according to [70,71], we can finally obtain the required total influence matrix and the importance and relation of each criterion in Table 8 and the causal graph of key criteria is illustrated in Figure 6.total influence matrix and the importance and relation of each criterion in Table 8 and the causal graph of key criteria is illustrated in Figure 6.Table 8.Total impact matrix established using criteria.

Analysis Results and Discussions
After discussion with the experts, it was decided to select the top eight criteria based on the ranking of importance (D + R) in Table 9 as the key criteria.The criteria in order of importance are as follows: "A7.Influencer's Reputation," "A1.Credibility," "A4.Degree of Key Opinion Influence," "A2.Attractiveness," "A6.Popularity," "A5.Consistency between influencers and brands," "A3.Fan Engagement Level," and "B3.Informativeness."These criteria are crucial for attracting consumer attention to influencers.

Analysis Results and Discussions
After discussion with the experts, it was decided to select the top eight criteria based on the ranking of importance (D + R) in Table 9 as the key criteria.The criteria in order of importance are as follows: "A7.Influencer's Reputation", "A1.Credibility", "A4.Degree of Key Opinion Influence", "A2.Attractiveness", "A6.Popularity", "A5.Consistency between influencers and brands", "A3.Fan Engagement Level", and "B3.Informativeness".These criteria are crucial for attracting consumer attention to influencers.Among them, seven out of the eight key criteria belong to Dimension A "Influencer Characteristics".This indicates that the criteria under the dimension of "Influencer Characteristics" are relatively important and have a larger proportion.
To classify the criteria as "cause" or "effect", the positive or negative value of the row-column difference (D − R) is usually considered.If the row-column difference is positive, it indicates that the criterion tends to "influence other criteria" (meaning "cause").If the row-column difference is negative, it indicates that the criterion tends to be "affected by other criteria" (meaning "effect").The causal characteristics of the criteria are summarized in Table 10.

Key Dimensions Analysis
Based on the research results and analysis shown in Figure 4, the ranking of importance for the dimensions is as follows: "C.Consumer Psychological Factors", "B.Content Characteristics", "A.Influencer Characteristics", and "D.Platform Selection".From the causal diagram of the dimensions, it is observed that "A.Influencer Characteristics" and "C.Consumer Psychological Factors" mutually influence each other, with "A.Influencer Characteristics" having a greater impact on "C.Consumer Psychological Factors".Based on this, it can be inferred that if one wants to improve the key factors for attracting consumer attention to influencers, it is possible through the element of "Influencer Characteristics".
Based on this result, it can be deduced that in influencer marketing, brands aim to achieve marketing objectives by selecting suitable influencers, such as increasing brand awareness, encouraging product trials by consumers [61], and leveraging influencer recommendations and sharing to influence consumer purchase decisions.However, the "Influencer Characteristics" play a crucial role in attracting consumer attention to influencers.For consumers, whether they receive and adopt the messages conveyed by influencers depends on the authenticity of the influencers' personality traits, behavior, and creative content.According to [72], authenticity refers to the genuineness, honesty, and openness of influencers towards their followers.Authenticity helps influencers establish new connections with their followers and contributes to building relationships between followers and brands.Therefore, an influencer with authenticity is perceived by consumers as providing a natural and non-pretentious experience, which leads to trust and positive feelings towards the influencer.In addition to authentically presenting personal characteristics, influencers use their expertise in managing types and shaping content styles to reinforce their own uniqueness.Brands can also plan marketing strategies by selecting specific social platforms based on the type of influencer's expertise and their preferences.

For SMIs
Based on the importance ranking in Table 9, the most important criteria are "Trustworthiness" and "Influencer Reputation".The relevance analysis reveals that "Credibility" is the primary underlying factor influencing consumer attention to influencers.This result indicates that the "trust consumers have in the influencer and their content" is the first and foremost important factor for brands when selecting influencers to ensure consumer interest in their sponsored content and to maximize the effectiveness of influencer marketing.
For influencers, starting with building trust and creating authentic content allows them to gain the trust of a larger audience and build a reputation in their field.
Furthermore, "Credibility" is primarily influenced by three key criteria: "Influencer Reputation", "Degree of Key Opinion Influence" and "Attractiveness", in descending order of impact.Therefore, if there is a need to enhance the "Credibility" of an influencer, improving these three criteria can help elevate the level of trust.

For Businesses
Consumers typically use social media platforms to follow influencers' lives and receive information they share.In the absence of face-to-face interactions, authenticity becomes a primary reason for consumers to trust influencers.Ref. [72] emphasizes the importance of "authenticity", where the influencers' own thoughts and perspectives are seen as reliable sources of information rather than simply reposting content from others.Therefore, the trustworthiness of influencers is especially crucial for consumers.When consumers trust an influencer and perceive the information they provide as authentic and reliable, the messages become more persuasive.This aligns with [73]'s assertion that if a popular influencer promotes a product on Instagram, the product will receive the influencer's positive endorsement, positively influencing followers' attitudes toward the product and, consequently, influencing their purchasing behavior.
Businesses can confirm the accuracy of content provided by influencers and assess whether the audience perceives the influencer as honest, well-founded, and trustworthy through audience feedback and comments.Trustworthiness and expertise are dimensions used to measure trust in endorsers [74].This ensures that the chosen influencers are trusted by consumers.Additionally, in terms of content creation for collaborations, idea generators should give influencers creative freedom, rather than forcing pre-determined scripts or content, to maintain the authentic image of both the influencer and the brand.

Comparing Perspectives from the Brand and Consumer Sides
Based on these results (in Table 11), the considerations of the brand encompass four main dimensions: influencer characteristics, content characteristics, consumer psychological factors, and platform selection.From the consumer's perspective, the most significant aspect is the influencer's characteristics, while the other dimensions are less emphasized.According to the brand's opinions, they identify 14 essential criteria, whereas consumers consider the top 8 criteria to be the most crucial.It is evident that consumers prioritize the personal attributes of influencers, including the influencer's reputation (A7), credibility (A1), degree of key opinion influence (A4), attractiveness (A2), popularity (A6), consistency between influencers and brands (A5), fan engagement level (A3), and informativeness (B3).The present research indicates that prioritizing consumer-endorser identification, which adopts a customer-focused approach to selecting celebrity endorsers, serves as a more effective predictor of endorsement success compared to solely relying on a productfocused approach based on the product-endorser fit [14].The perspective presented in [14]'s research aligns well with our study's viewpoint, as adopting a customer-focused approach can assist brands or companies in allocating resources to customer-focused criteria, facilitating the formulation of effective marketing strategies.
In influencer marketing, brands aim to achieve marketing objectives such as increasing brand awareness, encouraging consumers to try products [61], and even influencing consumers' purchasing decisions through recommendations and sharing by influencers.However, what characteristics do influencers need to attract target audiences and convey messages?This highlights that "influencer characteristics" are the focal point for attracting consumer attention to influencers.
For consumers, whether they receive or adopt the messages conveyed by influencers depends on the authenticity of the influencers' personality traits, behavior, and creative content.According to [72], authenticity means that influencers are sincere, honest, and open to their followers.Authenticity enables influencers to establish new connections with followers and helps build relationships between followers and brands.Therefore, an authentic influencer is perceived by consumers as providing a natural and genuine experience, leading to trust and favorability towards the influencer.
Echoing the expert opinions from the aforementioned questionnaire interviews, besides authentically presenting their personal characteristics, influencers enhance their traits by leveraging their expertise in content creation and shaping content styles.Brands can also plan strategies based on the specific social media platforms where influencers excel in managing their content.

Conclusions and Remarks
Based on the research results, it can be inferred that the most crucial criteria are "Trustworthiness" and "Influential Reputation of the Influencer".From the perspective of association, "Trustworthiness" is the "cause", serving as the primary root influencing consumers' attention towards influencers.This signifies that for brands when selecting influencers, whether the influencer and their content are trusted by consumers becomes the foremost factor.This is to ensure that consumers will be interested in the influencer's sponsored content, thereby leveraging the benefits of influencer marketing.Therefore, "Trustworthiness" is used as the starting point for evaluating and choosing influencers.
For influencers, commencing with building authentic content based on trust can engender greater trust from the audience and develop a positive reputation in the field.Among the key criteria, "Trustworthiness" is primarily influenced by three key criteria, ranked in order of their impact: "Influential Reputation of the Influencer", "Degree of Influential Opinions", and "Attractiveness".Hence, improvement measures can be comprehensively considered alongside these criteria to enhance influencer trustworthiness.
From the perspective of influencers, this study proposes three improvement suggestions, as explained below: 1.
Considering "Influential Reputation of the Influencer": Influencers should consistently create content within their niche that accumulates more positive comments/evaluations than negative ones.This builds trust with both brands and new audiences, thereby gaining more attention from viewers and more collaboration opportunities with brands.

2.
Considering the "Degree of Influential Opinions": Besides clearly defining their niche, influencers should leverage their knowledge and experience within their field.This not only enhances the usefulness and richness of their content but also strengthens the impact and acceptance of brands and products, prompting consumers to adopt and follow the influencer's opinions.

3.
Considering "Attractiveness": Through content that captivates and exposes audiences due to social trends and personal charisma, influencers attract viewers.The presence of attracted viewers indicates that the influencer is well-liked and approved by the audience, ultimately reflecting the audience's trust in the influencer.
Based on the collected valid questionnaires from the DEMATEL survey, the age group of consumers interested in influencers falls between 21 to 39 years old.The top three social platforms they use are YouTube, Facebook, and Instagram.About eighty percent of consumers use two or more social platforms to follow influencer content.Currently, the domestic influencer's top three social platforms are Instagram, Facebook, and YouTube.YouTube's relatively lower usage is due to its higher technical threshold and time cost for management.Consequently, newcomers in the influencer field often prioritize Instagram or Facebook.This leads to a smaller number of influencers who actively manage YouTube channels.
The statistical results of influencer platform usage differ slightly from the statistics of this study's surveyed consumers who are interested in influencers and engage in purchasing behavior.This indicates that a larger number of people make purchases through watching YouTube sponsorships, making the study results more representative.The higher usage of YouTube can be attributed to its popularity in Taiwan, as well as its broader age range compared to Instagram.YouTube's content diversity (long and short videos, imagetext posts, subscription model) makes it easier for consumers to understand influencers' personalities.It also enhances content experiences and interactions, surpassing Instagram and Facebook.This, in turn, generates more discussions and traffic, making YouTube a suitable platform for engaging with consumers.
Therefore, it is suggested that influencers initially focus on Facebook and Instagram to share real-life experiences, create authentic content, and gather trust from viewers to build a positive reputation and fan base.As the fan base grows, influencers can then venture into YouTube.This approach provides a diversified way of presenting content.Managing multiple social platforms increases exposure range, and for example, different platforms can be used for different types of content based on the influencer's style, resources, budget, and audience characteristics.YouTube, for instance, is suitable for longer, thematic videos that offer real-life experiences and attract audiences interested in specific topics.Facebook can deliver comprehensive image-text information to a wider target audience, leading to short-term exposure benefits.Instagram primarily features images and short videos, allowing for a visually diverse presentation, as well as the ability to share real-time life experiences, quickly capturing the audience's attention.

Contributions
In this study, we introduce a novel two-stage research approach that combines the Delphi and DEMATEL methodologies.Traditionally, the Delphi method has been utilized independently to address expert disagreements.By integrating it with the DEMATEL method, we offer a more comprehensive exploration of practical problems and extend the "solution space" available to decision-makers for subsequent improvements.Our systematic research framework enhances the feasibility of practical applications and facilitates understanding of dynamic improvement directions in opinions.This innovative approach represents the primary contribution of this research.In practical applications, the first stage employs the Delphi method with 11 experts experienced in marketing and influencers.This approach integrates practitioner insights, enhancing the credibility and applicability of our findings.Additionally, surveys with 174 consumers who have actual purchasing experience influenced by influencers fill a gap in the existing literature focused primarily on intentions and attitudes.We also present an operational assessment framework for selecting influencers across social media platforms, addressing the practical needs of businesses seeking effective influencer marketing strategies.Our study bridges the gap between theoretical methods and practical applications in influencer marketing.By applying theoretical methods to real-world contexts, we validate the applicability of research methods in this field and offer valuable insights for both academics and practitioners.Overall, our innovative approach and comprehensive analysis significantly contribute to advancing influencer marketing research.

Research Limitations
This study solely develops an evaluation framework for assessing consumer attention to influencers, lacking validation through actual case studies.Future research should compare and validate influencers within the same industry to discern differences and formulate pertinent strategies for influencer marketing.Moreover, the study exclusively examines influencer characteristics, neglecting other potential influencing factors like brand and product attributes.Future researchers could incorporate these factors to explore additional influencing dynamics.

Mathematics 2024 , 2 Figure 1 .
Figure 1.The most popular social media platforms worldwide.

Figure 2 .
Figure 2. Taiwan's most used social media platforms.

Figure 1 . 21 Figure 1 .
Figure 1.The most popular social media platforms worldwide.

Figure 2 .
Figure 2. Taiwan's most used social media platforms.

Figure 2 .
Figure 2. Taiwan's most used social media platforms.

Figure 3 .
Figure 3.The conceptual framework of this study.

Figure 3 .
Figure 3.The conceptual framework of this study.

( 2 )
Experts respond to several rounds of questionnaires, and the responses are aggregated and shared with the group after each round.(3)The experts can adjust their answers each round based on how they interpret the "group response" provided to them.(4) The ultimate result is a true consensus of what the group thinks.

Figure 4 .
Figure 4. Platforms used by consumers to follow influencers.

Figure 6 .
Figure 6.The causal graph of key criteria.

Figure 6 .
Figure 6.The causal graph of key criteria.

Table 1 .
Definition of criteria in influencer marketing.
3 ProfessionalismInfluencers' knowledge, skills, experience, and expertise allow them to make certain claims regarding specific topics.

Table 2 .
Dimension and criteria of preliminary research framework according to the literature review.

Table 3 .
The characteristics of the sample.

Table 4 .
Construction of the normalized direct influence matrix.

Table 5 .
Construction of the total influence matrix.

Table 6 .
Calculation of importance and relation.

Table 7 .
Dimensions for importance and correlation.

Table 6 .
Calculation of importance and relation.

Table 7 .
Dimensions for importance and correlation.

Table 8 .
Total impact matrix established using criteria.

Table 9 .
The final result of DEMETAL method ranking and importance and criticality of criteria.

Table 10 .
Key causal characteristics of criteria.

Table 11 .
The rankings of brand/influencer and customer sides.