Internet Celebrities’ Impact on Luxury Fashion Impulse Buying

: This study investigates how the endorsements of Internet celebrities (ICs) may drive consumer trust in their marketing campaigns, and subsequently affect impulse buying in relation to luxury fashion brands. Drawing on the framework of persuasion with a particular emphasis on the role of receivers, this study identiﬁes ﬁve main characteristics, namely, the popularity of ICs, identiﬁcation, IC adoration, social distance, and the perceived ﬁt that may contribute to promoting impulse buying. A survey was conducted with 585 followers of IC in China. The ﬁndings reveal that trust is an essential factor that affects impulse buying. Identiﬁcation and perceived ﬁt both signiﬁcantly contribute to increasing impulse buying through trust. Alternatively, large social distance may impair the relationship between trust and impulse buying. We conclude with implications for marketers that luxury fashion brands should seek cooperation not only with the most popular, but also with the most relevant ICs. An IC with a humble and relatable image can earn consumers’ trust and lead to an enhanced endorsement effect.


Introduction
In recent years, the emergence of social media has altered the advertising strategy of marketers by enabling interactive (two-way) communication with consumers [1], thus amplifying the effects of peer recommendation. Through social media activities, some consumers become online opinion leaders by sharing their lives and skills and gain the power to influence their followers [2], which gives rise to a new type of endorser: the Internet celebrity (IC). Since ICs share more in common with ordinary consumers than their traditional counterparts, their recommendations can appear more authentic and influential in building trust and promoting online sales [3]. As empowered by IC endorsement, the merchandise volume on Taobao (a large online retailer in China) in 2018 increased by 400% and reached over one hundred billion yuan in revenue. (Available online: http://www. cbndata.com/report/1433/detail?isReading=report&isreading=report&page=5, accessed on 10 May 2019).
ICs are effective in persuading purchasing and a growing number of e-commerce platforms now turn to ICs for cooperation [4]. In the online retailing context, consumers are able to respond more quickly to their changing moods [5] and tend to purchase products they did not plan to buy impulsively. Impulse buying defines the way in which people buy unreflectively and spontaneously without considering the reason for their purchase [6]; it takes up 40% of online purchases [5] and is potential for strong growth in e-commerce [7].
The literature and facts above indicate the importance of ICs' potential to encourage impulse buying, while there is a lack of research in this context. Existing literature on IC has led two main streams: (1) investigating ICs' personality traits [8] and formation of trust [9]; and (2) analyzing the success of ICs, including the accumulation of cultural capital [10], the ad disclosure strategy for improved attitude towards the advertisement [11,12], or ICs' content strategy for improving follower engagement [13]. With the widespread use of IC endorsements, research has been conducted to examine ICs' impact on planned purchase 1.
What is a suitable conceptual model that provides an accurate picture highlighting the main aspects of IC endorsement? 2.
What are the main factors of IC endorsement that affect consumers' impulse buying?
There are theoretical frameworks such as the technology acceptance model [30] and S-O-R framework [19,31] investigating online impulse purchases. While these studies have deepened our understanding of online impulse buying, a common thread across them is the need to further explore how IC-consumer interaction influences online impulse buying. Endorsements by ICs originate from the dissemination of recommendation information, whereby its effect depends on how consumers construe the information and relate to the information source [17]. Therefore, we aim to complete the whole picture of impulse buying considering the interaction between ICs and consumers. The literature on persuasion emphasizes the role of the source, the content disseminated, and the receiver [32][33][34]. Accordingly, we have discerned five factors: the source characteristic of ICs' popularity; the perceived fit between the IC and brand; the social distance between the consumer and the IC; the consumers' identification with the IC; and the consumer trait of IC adoration as antecedents of impulse buying intention in the IC endorsement process. We further uncovered the mechanism of the IC endorsement effect and proved that the links between these five factors and impulse buying are consolidated by the trust that people place in ICs.
We tested our hypotheses in the context of luxury fashion because it is the product category most closely related with ICs [35]. Moreover, since products that project a person's self-image, particularly those with a stronger symbolic and emotional meaning, are the most conducive to impulse buying [36], luxury fashion goods deserve further investigation in this context [37]. By applying structural equation modeling to a sample of 585 IC followers, our study makes three important contributions to theory and practice. First, it adds to the literature on impulse buying by going beyond individual and environmental factors and focusing on the social influence of ICs [20][21][22]. Second, although numerous studies have verified the important characteristics of an IC in shaping consumers' attitudes or purchase decisions (e.g., [12,[25][26][27]), few of them examined the interaction between ICs and consumers and have put consumers in a passive position. Thus, it remains unclear how consumers construe an IC may affect their decision to accept an endorsement. Our study has discerned consumer-related factors by introducing the framework of persuasion and suggests that the social distance between consumers and ICs, consumers' identification with and adoration of ICs affect their impulse buying intention. Finally, our study provides insights into the mediating role of consumers' trust toward ICs in the relationship between endorsement antecedents and impulse buying.

Internet Celebrity and Impulse Buying
Unlike traditional celebrities who gain public recognition through their successful performances in credentialed institutional settings (entertainment, sports, etc.), ICs become popular by branding themselves on social media platforms using videos, photos, and blogs [10,38]. By consistently posting self-generated content on fashion, beauty, and luxury topics, ICs have managed to become influencers because of their online social presence [2]. They have blurred the lines between product consumers and advertisers and have become a new information source. Compared to one-way formal channels like traditional advertisements, the immediate two-way interaction on social media between ICs and their followers connotes a certain closeness, making the endorsement more reliable [3]. The more followers an IC has, the greater the probability that their followers may re-post their image, thus expanding their social influence [39]. An IC's ability to attract a broad audience from various age groups, particularly their role in accelerating the flow of novel information, can be harnessed by advertisers for brand promotion. The success of ICs can be measured by their network size and their relative share of posts [40]. Previous studies have argued that trustworthiness, expertise, enthusiasm, and attractiveness [9,12,26,41] are all desirable characteristics.
More and more marketers are employing ICs to influence E-commerce users to generate purchase intention [13,41]. Related research on IC marketing has addressed several topics regarding ICs' likeability [42,43], ICs' advertisement disclosure strategy [44], and the endorsement effect of ICs in promoting attitudes toward advertisements and brands [45]. Since impulse buying is prevalent in the online context, it is worth investigating how to leverage the intimate connection ICs forge with their followers to motivate more spending by eliciting impulse buying behavior.
Impulse buying occurs when consumers feel a sudden, often powerful and persistent urge to buy something immediately [6]. Impulse buying depends on a set of individuallevel factors, including resources of money, time, and self-control [46]. The literature has proposed that time pressure, location, and product attributes and store environment can arouse impulse buying [21,22]. Studies that examined impulse buying in the context of e-commerce have identified website factors (product availability, visual design, website appeal, and ease of use) as important antecedents of impulsive consumption [19,47]. A few researchers have investigated social factors and have suggested that different cues, like the presence of others when shopping [48] and the para-social interaction online [14], play a crucial role in impulse buying. Our study, as a supplement, focuses on social factors embodied in the interaction between ICs and consumers, which may contribute to online impulse buying.

IC Endorsement and Persuasion
Due to rapid information exchange facilitated by modern technology, ICs gain their popularity mainly through information propagation and follower accumulation. It is thus essential to understand how their followers are persuaded and the way in which endorsement information is processed. IC endorsement is a typical form of persuasive communication-a campaign through which receivers accept a certain view or take certain actions. When choosing high-priced products that signal prestige, such as luxury fashion, consumers tend to pay more attention to recommendations [49]; therefore, efficient communication and persuasion are important. The attitude and behavior formation process of consumers can be explained using the persuasion framework, according to which the three principal factors that affect communication and decision making are the information source, information, and the information receiver, with the main consideration of "who says what to whom" [32][33][34]. Thus, in this study, ICs' persuasion effect on luxury fashion purchasing is captured from three dimensions: the characteristics of the source (ICs), the information conveyed (the message of luxury fashion), and the receiver (consumers). With the rise of social media as the central medium for brand-consumer interaction, researchers are increasingly interested in how people are persuaded in the context of an online commercial. Zhang, et al. [50] drew upon the persuasion framework to test the factors that influence consumers' participation level and brand loyalty through brand microblogs. Liang and Tukachinsky [51] extended the persuasion framework to participatory websites where user-generated reviews can be mutually influential, to explore the effect of emotion on attitude persistence. Likewise, since the IC endorsement is a form of online commercial with the goal of persuading consumers into forming a positive brand attitude and making purchase decisions, we can apply the persuasion framework to clarify its effect.
There are numerous studies investigating the effect of celebrity endorsement. Bergkvist et al. [45] established the source credibility model which emphasized the importance of the source's expertise, trustworthiness, and attractiveness. The meaning-transfer model suggests that for meaning to be transferred the endorser should possess traits that are compatible with the brand [52], the basis on which Kamins [53] developed their match-up hypothesis, which contends that the congruence between the celebrity and the product can positively affect the attitude of consumers toward the advertisement. Further studies have shown that the attractiveness and expertise of endorsers are promising match-up factors (e.g., [54,55]). In the Internet era, scholars have attributed celebrities' success to popularity through the accumulation of cultural capital [10]. These theories, although widely applied, have mainly considered the source factors while paying little attention to the role of receivers. In an online context where pervasive interaction between ICs and consumers occurs, it is essential to understand how receivers' interpretation of their relationship with ICs may affect the persuasion process. As noted by Escalas and Bettman [56], consumers regard celebrities as a means to meet their affiliation needs and develop a stronger connection with the brand endorsed. It is thus proposed that identification and IC adoration are two additional driving factors that influence buying. Moreover, impulse buying is biased by proximity and people tend to be more dependent on the recommender when a small social distance exists [57].
Consequently, this study investigates the source trait of ICs' popularity, the receiver's trait of IC adoration, the perceived fit as embodied in the interaction of the source and information, and identification and social distance as embodied in the relationship between the source and the receiver, as factors affecting impulse buying. Although previous studies have assumed a direct effect among source factors on purchase behavior, recent studies on celebrity endorsements suggest that the effect is mediated by consumers' attitudes toward the celebrity-brand alliance [45]; thus, our study investigates the mediating role of trust. In the internet environment, trust is particularly important because computermediated technology may create the perception of risk due to the absence of meaningful relationships between parties [47]. On a computer screen there is little assurance of the expected product quality; trust can reduce uncertainty and serve as a mental shortcut to aid rapid and spontaneous decision making [58,59]. In the more general domain of electronic word-of-mouth, it is also suggested that, particularly for IC influencers, credibility plays an important role in purchasing behavior [15], since highly credible sources are perceived to be more trustworthy [3]. Thus, IC endorsements may have a positive effect on trust, which, in turn, may positively affect impulse buying.

Impulse Buying
Impulse buying is characterized as hedonic purchase behavior associated with feelings of pleasure and excitement rather than thinking and cognitive processing [60]. Generally, a buying decision is made under the conflict between desire and willpower, and when the desire to buy overpowers the ability to execute self-control, impulse buying occurs. Buying impulsiveness largely originates from thoughts of self-discrepancy and a desire for self-completion. When people encounter differences between how they see themselves and how they wish to be seen, they are motivated by strong materialistic values and believe that owning material goods is the way to enhance self-identity and satisfaction [36]. Hence, this study investigates luxury fashion products, which can most adequately capture the materialistic essence of impulse buying to satisfy self-image and affective emotions.

Trust
Although the Internet has overturned many established rules of business, earning consumers' trust to obtain a competitive advantage is a pervasive concern in many buyerseller relationships [61,62]. Trust is "the willingness of a party to be vulnerable to the actions of another party based on the expectation that the other will perform a particular action, irrespective of the ability to monitor or control that other party" [63]. It relates to beliefs in the integrity, benevolence, and ability of the source [64], and is strongly associated with attitudes toward buying and shopping behavior [3].
As pointed out by McEvily et al. [65], trust acts as a heuristic cue which can reduce cognitive effort during decision making. Since buying impulse is an irresistible urge dominated by affective rather than cognitive processes, trust can thus be an effective precursor for the establishment of buying impulse. Further, trust has attained a favorable position especially in online buyer-seller transactions characterized by uncertainty [58]. While impulse buying is perceived to be a "risky" decision which may result in decision errors, trust has been proven to be related to a willingness to take risks. It can facilitate transactions in the presence of uncertainty and release stress pertaining to impulsive behavior [66]. Therefore, it is proposed that trust will positively affect impulse buying.

Hypotheses 1 (H1).
Trust has a positive effect on impulse buying for luxury fashion brands.

ICs' Popularity
ICs with high levels of popularity are those who can spread information easily and reach a wide audience through online activities [10]. They occupy a central position on social media, which serves to amplify their reputation and increase their ability to influence others. ICs with high popularity are likely to be more disciplined since they may suffer more if their endorsement is perceived as unauthentic. Users can judge ICs' competence and credibility based on system-generated cues such as the number of followers or update frequency. A study by Edwards et al. [67] demonstrated that a higher Klout score (an objective measure of social influence) can lead to a greater perception of credibility toward the target and is important in establishing trust [68].
Moreover, the more popular ICs are, the greater the influence they can exert on the online community by capturing more followers. The large number of followers having a positive opinion of the IC acts as a bandwagon cue, signaling the collective choice and belief of the crowd [69]. As is indicated by bandwagon heuristics, people believe that ICs become popular for specific reasons, either due to their high level of expertise or their abilities [70]. When the opinions of ICs are adopted by many consumers, people may perceive them as trustworthy and form positive attitudes toward them. The effect of bandwagon cues can thus reduce caution, making the decision process quick and easy. Wei et al. [71] have further confirmed the mental mechanism underlying the effect of social influence on trust at the neurological level.
Therefore, consumers may be more susceptible to the recommendation and be willing to take risks when exposed to popular ICs.
Hypotheses 2 (H2). The popularity of ICs has a positive impact on trust.

Perceived Fit
ICs vary in their personality traits and styles; they post content from different domains and attract specific audiences. As a new branch of opinion leaders who make a living by consistently exploring and sharing the latest fashions, ICs consistently exhibit an expert image that tends to decrease consumers' perceived risk when seeking advice [72]. As proposed by the match-up hypothesis, the celebrity image and product features should be congruent for effective advertising [53]. The compatibility of an IC's style with the brand and sufficient knowledge of the brand can maximize the credibility of the endorser and make the endorsement believable. Pradhan et al. [16] indicated that the fit between the personality of the brand and the celebrity had a significant influence on brand attitude and could reduce perceived risk. Brands may suffer a loss if they violate the congruency principle since this may reduce the perceived product reliability and break consumers' trust [73].
Past studies have also shown that the perceived accuracy derived from information processing can positively affect impulse buying [74], and such accuracy can be consolidated through consumers' perception of the fit between ICs and products-mainly reflected as ICs' attractiveness and expertise [55]. In the context of luxury fashion, where the product is highly priced, an IC's image of attractiveness and expertise is especially important. Conversely, a perceived dissimilarity between the IC and the brand may increase consumer skepticism and lead to more careful consideration [12], which may impede the formation of impulse buying behavior. This leads to the following hypotheses.

Hypotheses 3a (H3a). Perceived fit has a positive impact on trust.
Hypotheses 3b (H3b). Perceived fit has a positive impact on impulse buying toward luxury fashion brands.

Identification
Identification is a fundamental form of social exchange and represents an emotional tie with others. It emphasizes the importance of member similarity [75], which derives from the recognition that one shares similar interests, characteristics, or values with others. In the context of brand community, López et al. [75] suggested that identification exerts a key impact on trust and brand loyalty and acts as an important predictor of brand success. In the similar context of social commerce, we propose that identification may establish trust in the IC. Further, consumer behavior can be influenced by value transformation through identification. In addition to commonality of feeling, identification also arises from the desire to emulate [53]. According to the social constructionist theory, people perceive possessions as their self-extension and a reflection of their self-identity [36]. They may strive to become whom they wish to be by imitating and emulating others to promote their self-image once they realize that there is a gap between their "ideal" and "actual" self. The more they are prone to use material goods to compensate for the inadequacies of their self-concept, the more likely they are to act impulsively [36]. Therefore, consumers may find the luxury fashion endorsed by the ICs that they identify with more tempting, and may try to own these products as a shortcut to realizing their "ideal selves," which can lead to impulse buying.
Hypotheses 4a (H4a). Identification has a positive effect on trust.
Hypotheses 4b (H4b). Identification has a positive effect on impulse buying in relation to luxury fashion brands.

Social Distance
Social distance is the "degree of sympathetic understanding that functions between person and person" [76]. It refers to consumers' perceived interpersonal distance from ICs, including cognitive, emotional, and attitudinal distance based on self-concept and social differences. Social distance may trigger various construal levels, which are crucial in influ-encing consumer behavior, decision making and self-control [77]. Construal level depicts the way people mentally interpret an event. When people are faced with socially distant others, they put them on a higher construal level by activating a mindset to understand events based on abstract, primary, and global aspects rather than concrete and detailed ones [78]. The activation of high-construal levels leads individuals to make decisions in accordance with their primary and central goals rather than secondary, incidental factors. Thus, high-level construal level often involves more effortful, deliberate, and rational thinking [79] that may lead to less positive evaluations of temptations and trigger stronger self-control [57], thereby restraining impulse buying.
As proposed by Tesser [80] and Liviatan et al. [78], social distance is related to interpersonal similarity; similarity is thus used as the measure of social distance in this study. Individuals prefer to be in contact with those who share similar psychological features and perceive them to be more reliable and credible. This is essential for trust establishment and information flow [81]. Within a social network, the similarity between the lifestyle of a consumer and the producer of an advert can positively affect attitude formation and information reception and can foster a high level of trust [82]. This is consistent with Leonidou et al. [83] who found that psychological proximity can impact trust and relationship satisfaction.
Hypotheses 5a (H5a). Social distance has a negative impact on trust.
Hypotheses 5b (H5b). Social distance has a negative effect on impulse buying in relation to luxury fashion brands.

IC Adoration
IC adoration is a personal trait which describes the tendency of having excessive admiration for or devotion toward ICs [84]. In modern society, consumers' adoration toward celebrities has been exploited by marketers. Previous work in branding literature has raised the similar concept of brand love which defines consumers' passionate emotional attachment for the brand [85], and confirmed the role brand love plays in predicting willingness to pay and positive word-of-mouth [86], based on which we could infer that emotional attachment to adoration for ICs could similarly promote purchase intention. Moreover, it is evident that consumers engage in impulse buying for entertainment, novelty, and surprise, which coincides with ICs' hedonic characteristics of portraying a distinctive personality, enjoying over-night fame, and presenting attractive online content. According to Yang, et al. [22], the emotional state of excessive admiration for ICs is congruent with the hedonic nature of impulse buying. In addition, higher propensity toward celebrity adoration is significantly correlated with lower levels of self-esteem, and people usually turn to impulsive buying to cope with such negative feelings. Therefore, people with greater adoration toward ICs are more susceptible to the products they recommend and are prone to impulse buying.
Hypotheses 6 (H6). IC adoration has a positive effect on impulse buying in relation to luxury fashion brands.

Proposed Theoretical Model
Based on the theoretical view, Figure 1 shows the relationships between the constructs and the respective hypotheses.
Hypotheses 6 (H6). IC adoration has a positive effect on impulse buying in relation to luxury fashion brands.

Proposed Theoretical Model
Based on the theoretical view, Figure 1 shows the relationships between the constructs and the respective hypotheses.

Measures
The research constructs were adapted from validated scales in the current literature. ICs' popularity was measured by three items adapted from Chen et al. [87] in addition to number of fans [88]. Chen et al. [64] reported a Cronbach's alpha of 0.811 and content validity of 0.79. The five-item measure of perceived fit was adapted from Till and Busler [55] and Ohanian [89]. Our scale simplified the original into three summarized match-up dimensions, namely expertise, attractiveness, and trustworthiness. Social distance was measured by a four-item scale adapted from McCroskey et al. [90] with a combination of the dimension of social status as indicated in Bourdieu [91]. IC adoration was measured using four items adapted from Maltby et al. [92], who reported a Cronbach's alpha of 0.93 for the scale. Identification was measured by a five-item scale developed by Schramm and Hartmann [93], which emphasized identification of the role with inner and outer appearance and the success of the character, and this was combined with Auter and Palmgreen's [94] audience-persona interaction scale (with a reported Cronbach's alpha of 0.84). The five-item scale of trust was developed using Xiao and Benbasat's [95] operational definitions of trust. The four-item scale of impulse buying was created using two items taken directly from Verhagen and Van Dolen's [5] scale (with a reported composite reliability of 0.80) in combination with a definition of impulse buying [6]. All constructs were measured by reflective indicators since changes in the constructs are reflected in changes in observable indicators.
The reliability and validity of the scale were confirmed through a pre-test with 245 respondents. It is shown that each construct has an acceptable Cronbach's alpha value ranging from 0.73-0.92, with the social distance dimension being the lowest, and the average variance extracted (AVE) for all the constructs being above the threshold of 0.5 [96]. Finally, most students reported a clear and straightforward use of language and a reasonable length of the questionnaire.
All items were measured on a seven-point Likert scale (1 = strongly disagree to 7 = strongly agree). Table 1 gives an overview of the descriptive statistics of all indicators and the context in which they were used in the original scale.

Measures
The research constructs were adapted from validated scales in the current literature. ICs' popularity was measured by three items adapted from Chen et al. [87] in addition to number of fans [88]. Chen et al. [64] reported a Cronbach's alpha of 0.811 and content validity of 0.79. The five-item measure of perceived fit was adapted from Till and Busler [55] and Ohanian [89]. Our scale simplified the original into three summarized match-up dimensions, namely expertise, attractiveness, and trustworthiness. Social distance was measured by a four-item scale adapted from McCroskey et al. [90] with a combination of the dimension of social status as indicated in Bourdieu [91]. IC adoration was measured using four items adapted from Maltby et al. [92], who reported a Cronbach's alpha of 0.93 for the scale. Identification was measured by a five-item scale developed by Schramm and Hartmann [93], which emphasized identification of the role with inner and outer appearance and the success of the character, and this was combined with Auter and Palmgreen's [94] audience-persona interaction scale (with a reported Cronbach's alpha of 0.84). The fiveitem scale of trust was developed using Xiao and Benbasat's [95] operational definitions of trust. The four-item scale of impulse buying was created using two items taken directly from Verhagen and Van Dolen's [5] scale (with a reported composite reliability of 0.80) in combination with a definition of impulse buying [6]. All constructs were measured by reflective indicators since changes in the constructs are reflected in changes in observable indicators.
The reliability and validity of the scale were confirmed through a pre-test with 245 respondents. It is shown that each construct has an acceptable Cronbach's alpha value ranging from 0.73-0.92, with the social distance dimension being the lowest, and the average variance extracted (AVE) for all the constructs being above the threshold of 0.5 [96]. Finally, most students reported a clear and straightforward use of language and a reasonable length of the questionnaire.
All items were measured on a seven-point Likert scale (1 = strongly disagree to 7 = strongly agree). Table 1 gives an overview of the descriptive statistics of all indicators and the context in which they were used in the original scale.

Participants and Procedure
The questionnaire was designed on Survey STAR (https://www.wjx.cn, accessed on 10 June 2018, the largest survey platform in China) both for the pre-test and for the formal survey, and the links were shared on several large social networking sites (including WeChat, QQ, and Weibo) to recruit participants. The formal questionnaire consisted of three parts. In the discrimination part, participants first read the following instruction: Luxury fashion are products and services which possess higher levels of quality, taste, and aspiration than other goods in the category, typically represented by Michael Kors, Coach, Furla, and Daniel Wellington. However, they are priced well below traditional luxuries like Chanel and Gucci and are thus more accessible [97]. They then read: Internet celebrities are people "amping up" their popularity on the internet using technologies such as video, blogs, and social networking sites. They include not only good-looking bloggers but also opinion leaders or experts in all fields such as gaming, food, pets, fashion, and photography [38]. After the above guidance, the participants were asked to select the luxury fashion brand(s) that they recognize from ten named brands (including Michael Kors, Coach, Tory Burch, and Kate Spade, among others.) and answer the screening instruction, "Please write down the IC you are most familiar with." It was thereby ensured that our survey was administered only to respondents who were familiar with the context. Through prior focus group interviews with ten consumers, it was guaranteed that the ten named brands were similar in terms of market positioning and price levels with relatively high brand awareness. The participants were then guided with the following instruction: Suppose that you are browsing a social commerce platform when you find that the IC whose name you just wrote down is recommending a luxury fashion product from the brand you are most familiar with. It can be apparel, accessories, handbags, or shoes. Now please answer the following questions based on this scenario. In this session, data on trust, impulse buying, and five antecedent factors were collected. The scenario instructions were a replication of Tran et al. [98] and were proved to be comprehensible in the pre-test. Finally, personal information, including sex, age, monthly income, and level of education, was recorded.
Data were collected between July and August 2018. A total of 692 respondents participated in our survey for a 50% chance of winning a bonus of 1 RMB. Most of them were undergraduate and graduate students from Chinese universities. A small portion of elder participants with sufficient knowledge of ICs and luxury fashion brands was also included. A total of 107 responses were removed because they had either too long or too short response times, a lack of knowledge about what luxury fashion brands are, or were unable to name an IC (a fictitious name or the name of a traditional celebrity). As presented in Table 2, 81.4% of the valid respondents were younger than 30, and 58.8% of respondents were females. The demographic characteristic of the sample is consistent with China's Internet Celebrity Economy Development Report in 2018, which showed that up until 2018, more than 80% of IC fans were millennials (Available online: http: //www.iresearchchina.com/content/details8_46713.html, accessed on 16 March 2019). Therefore, our sample was representative.

Statistical Technique
The data were analyzed using the partial least squares-structural equation modeling (PLS-SEM) approach supported by the most widely used software, SmartPLS ® 3.0 [96]. PLS-SEM evaluates the model's quality by its predictive capability. The partial least squares (PLS) method was suitable for our analysis because it does not require the data to be normally distributed [99]. Moreover, the PLS method is superior in analyzing complex models compared to CB-SEM [96]. Table 3 indicates that all constructs achieved internal consistency reliability, with a Cronbach's alpha coefficient ranging from 0.844-0.937 and composite reliability (CR) scores exceeding the acceptable level of 0.7 [96]. Convergent validity was also acceptable when compared to the threshold of the AVE of 0.5, ranging from 0.664-0.826. The factor item loadings of the constructs were all above 0.6. The results indicated that convergent validity was achieved, and all measurement items were able to reflect the respective constructs appropriately [96]. A hetero-trait-mono-trait ratio of correlations (HTMT) test recommended by Henseler, et al. [100] was conducted to confirm discriminant validity. This shows that all HTMT ratios are well below the most conservative threshold of 0.85, ranging from 0.10-0.62, with those for trust and impulse buying being the highest. A bootstrapping procedure was also conducted to check if the HTMT statistic is significantly different from 1 with a subsample of 5000 [96]. The results showed that none of the confidence intervals contained the value of 1, which confirmed the distinction between the constructs. In summary, the results of the measurement model test, including internal consistency, convergent, and discriminant validity, were satisfactory.

Measurement Model Assessment
Finally, the standardized root mean square residual (SRMR) criterion was applied to examine model-fit and a value of 0.058 was found. Since an SRMR value of less than 0.08 indicates a good fit [96], our model achieved a good fit with the data.

Structural Model Assessment and Hypotheses Testing
The structural model was assessed based on its predictive capability, according to the R2 values, the Q2 values, and the significance of path coefficients. As shown in Table 4, the variance inflation factors (VIF) for all the predictors are below 3.0, so there is no threat of collinearity [99]. The coefficient of the determinants (R2) is commonly referred to as an indicator of predictive accuracy. Since the R2 of 0.2 is acceptable in the discipline of consumer behavior [96], the measure indicated high consistency, showing that 38% of impulse buying is a result of trust, and all the exogenous constructs account for 36% of the variance in trust. The model's predictive accuracy was further assessed based on a blindfolding calculation. The cross-validated redundancy (Q2) values of the endogenous constructs were both above zero (see Table 5). These results showed that exogenous constructs have high accuracy and predictive relevance [96].  The bootstrapping procedure was set at 5000 samples to examine the significance of the path coefficient [96]. The results in Table 4 showed that all the path coefficients are significant except for the Identification-Impulse buying and the Perceived fit-Impulse buying paths. Specifically, trust had a significant positive effect on impulse buying (β = 0.501, p < 0.001), thus providing support for H1. IC popularity had a significant and positive effect on trust (β = 0.190, p < 0.001), which supports H2. Perceived fit had a significant and positive effect on trust (β = 0.303, p < 0.001), but it had no significant influence on impulse buying (β = 0.050, p = 0.25). Hence, H3a was supported and H3b was rejected. Identification had a positive effect on trust (β = 0.281, p < 0.001), while there was no significant effect on impulse buying (β = −0.061, p = 0.19), which supports H4a and rejects H4b. Social distance had a significant negative influence on trust (β = −0.109, p < 0.001) and a significant negative effect on impulse buying (β = −0.113, p < 0.001), as expected. Therefore, H5a and H5b were supported. IC adoration had a significant positive effect on impulse buying (β = 0.199, p < 0.001), which supports H6. Figure 2 presents the SmartPLS model and the results yielded by the PLS algorithm.

Mediation Analysis
The mediation role of trust was examined through a mediation analysis with 5000 bootstrap samples. Following the two-step analysis procedure proposed by Nitzl, et al. [101], we first tested the indirect effect of the relationship between the exogenous and endogenous constructs and examined the type of mediation (full or partial) in the second step. As presented in Table 6, the indirect effect of identification, the ICs' popularity, perceived fit and social distance on impulse buying were all significant, as none of the 95% confidence intervals include zero. The direct effect of the above relationships was then examined and the results show that only the direct effect of social distance on impulse buying was significant (t = 3.266, p < 0.001). Therefore, trust partially mediates the relationship between social distance and impulse buying and fully mediates the identification,

Mediation Analysis
The mediation role of trust was examined through a mediation analysis with 5000 bootstrap samples. Following the two-step analysis procedure proposed by Nitzl, et al. [101], we first tested the indirect effect of the relationship between the exogenous and endogenous constructs and examined the type of mediation (full or partial) in the second step. As presented in Table 6, the indirect effect of identification, the ICs' popularity, perceived fit and social distance on impulse buying were all significant, as none of the 95% confidence intervals include zero. The direct effect of the above relationships was then examined and the results show that only the direct effect of social distance on impulse buying was significant (t = 3.266, p < 0.001). Therefore, trust partially mediates the relationship between social distance and impulse buying and fully mediates the identification, perceived fit, and ICs' popularity in relation to impulse buying. The product of the direct and indirect effect of social distance (−0.113 × −0.056 = 0.006) was finally computed. The sign of the product was positive, revealing complementary mediation of the relationship between social distance and impulse buying.

Discussion
This study proposes a global model including the shared perspectives of the source (ICs), the receiver (consumers), and the information (the luxury fashion brand) based on the persuasion framework to identify the factors that mainly contribute to impulse buying.
The key findings are discussed below.
First, trust plays an essential mediating role in establishing impulse buying. This finding is consistent with Chen et al. [61] who demonstrated that trust in the recommender is the central mediator for online impulse buying driven by product-related and recommender-related signals. It is also in line with the argument of Smith et al. [102] that trust acts as the mediator of the perceived influence of a peer recommender on consumers' purchase decisions. This may reflect a difference in consumers' perception between the ICs and traditional celebrities. Traditional celebrities enjoy a comparably higher social status [52], and are therefore considered to be more prudent and thoughtful in cooperating with brands to maintain their long-term reputation. However, consumers lack such belief in ICs. Without formal certification, consumers may become confused when deciding whether the IC is reliable and thus hesitate when making purchase decisions. This indicates that cultivating consumers' trust is central to IC endorsement. By trusting, people may overcome perceived risks while holding beliefs that may rule out possible undesirable behavior by the ICs [58], including recommendations for bogus or poor quality products only for remuneration [44].
Second, trust must be nurtured to exert influence on impulse buying. In the dimension of IC, the source trait of ICs' popularity is positively related to trust. This finding is consistent with previous research suggesting that popularity is an indicator of a celebrity's trustworthiness, which is linked to purchase intention [39]. Since the internet is an open environment, consumers' opinion is typically affected by others, and highly popular ICs indicate that they are the preference of the majority and give rise to trust. The result also shows that the fit between IC and the brand may not directly contribute to impulse buying but play a critical role in affecting trust and indirectly influence impulse purchase. This finding highlights the perspective of Till and Busler [55], who confirmed that celebritybrand congruency is only effective in changing attitude, but not in directly changing purchase behavior. Our results signify that ICs should propagate the style congruent with that of luxury fashion to help consumers in self-representation.
Third, this study finds that a smaller social distance between the IC and consumers may increase trust and promote the occurrence of impulse buying. Since most ICs gain fame through the internet, they are perceived to be more accessible, available, and authentic compared to traditional celebrities [3]. ICs who strike an appropriate balance between being "aspirational" enough-like traditional celebrities with their "larger than life" image-and simultaneously maintain a down-to-earth "regular person" image to ensure relatability can impress consumers. Such a similar balance has also been witnessed in the previous work of López et al. [75] in achieving identification in brand community. This suggests that, besides the sense of connection and shared vision which capture the homogeneity between the target and the consumers [103], the need for uniqueness also indispensably contributes to identification, i.e., consumers need to feel connected while maintaining their distinctiveness from other community members to develop identification. However, identification has no direct influence on impulse buying but only has direct influence on trust. This may be explained by Rook [6], who argued that identification is related to the transformation of personal value, which is the core of human belief systems that determine long-term behavior. Therefore, it will not work in eliciting spontaneous and impulse actions.
Finally, in the receiver's dimension, the consumers' propensity for adoration of ICs contributes most significantly to impulse buying. This result follows previous findings that people are likely to form purchase intentions involving the celebrities they adore [84]. This implies that people's self-oriented motivation plays an essential role in influencing shopping behavior [104]. Unlike other factors that are partially or fully mediated by trust, IC adoration can lead to impulse buying directly, given the fact that a psychological state of emotional attachment may impede the willingness to withstand impulse buying [22].

Conclusions
This research provides new perspectives to help marketers induce consumers' impulse buying intentions for luxury fashion brands by employing IC endorsement. Drawing on the persuasion framework, this study provides a theoretical foundation for understanding factors that induce impulse buying. Consumers tend to trust the ICs with whom they identify, who are popular, whom they feel close to, and who fit well with the brand endorsed. Next, trust in ICs can positively affect impulse buying. Alternatively, consumers' adoration of ICs may not determine trust, but directly affect impulse buying.

Theoretical Implications
Our study provides several theoretical contributions for researchers in related areas of interest. First, this research develops a model, in the context of the emerging importance of ICs, to capture the process of impulse buying. Although various studies in e-commerce have contributed to explaining impulse buying, most of them discussed influential factors on individual or environmental levels [20][21][22], while neglecting the social factor of IC endorsement. This study highlights how ICs have an influence on consumers' impulse purchase decisions, which extends the work of Aragoncillo and Orús [105] in the online e-commerce context, elucidating the influence of IC endorsement on impulse buying. Moreover, existing studies have mainly examined the endorsement effect in relation to consumers' attitudes or brand evaluations [13,45], while the effect on impulse buying has not been fully discussed. This study contributes a novel conceptual model by identifying the main factors related to IC endorsement on impulse buying.
Second, this study provides a new and feasible theoretical perspective to depict consumers' purchase behavior, integrating ICs' popularity, IC-brand fit, IC adoration, social distance, and identification within an extended persuasion framework. Prior literature often portrayed the celebrity endorsement effect as being dominated by celebrities themselves [12,24,26,28], and little research paid attention to the role of consumers, whose interaction with the celebrities would induce impulse buying online. This study shows a more integral viewpoint on IC endorsement from the shared perspectives of the source, information, and receiver. Our work also adds to the result of Torres, et al. [8] in that, besides the source-related factors that have already been emphasized, it discerns social distance and identification as factors that capture consumers' perceived sense of relatedness with ICs. Moreover, in their work regarding the formation of identification in the context of brand community, López et al. [75] proposed that both consumers' need for uniqueness and need for distinctiveness contribute to the formation of brand identification. They have also argued that, for small brands which are not as widespread as big brands and are thus strong in differentiation, people with a high need for uniqueness may find equilibrium between affiliation and distinctiveness needs. In this regard, since ICs are newly born celebrities with a much smaller audience than traditional celebrities, their followers may not be disturbed by concern for uniqueness, and those with a high need for uniqueness may find more identification with the ICs and thus are more prone to become involved in impulse buying.
Finally, this study expands the literature on trust whereby ICs have emerged as an important determinant of consumers' impulse buying, and highlights trust as a potential bridge in the novel context of IC endorsement. The results suggest that ICs' endorsement factors influences impulse buying behavior through the mediating role of trust. Few studies have examined the mechanism through which the endorsement takes effect. The empirical work extends Martensen's [25] work linking endorsement antecedents and impulse buying by adding the mediating construct of trust.

Managerial Implications
Our study provides guidance for luxury brands from three perspectives. First, it provides brands with criteria to follow when selecting an appropriate IC. For instance, the popularity of ICs and consumers' identification can both lead to the formation of trust, which is essential in establishing impulse buying. Therefore, brands can use the number of followers, as a convenient indicator of how popular an IC is, to decide on cooperation. Since consumers in developing countries like China have high public self-consciousness and are extremely susceptible to social pressure [106], brands should also prioritize ICs with high popularity to garner peer recognition. While employing a highly popular IC may be costlier than employing an IC with low popularity, the information delivered by the former can be more influential. Furthermore, as luxury in China is viewed as an iconic symbol of identity [107], brands should choose ICs with whom consumers identify and share common beliefs, primarily those who lead an aspirational and positive lifestyle.
Second, our study provides brands with the guidance for cultivating effective ICs. Since consumers in collectivistic cultures tend to define themselves through their relationships with others, they desire intimate connections through seemingly real dialog with ICs. Our finding suggests that social closeness is important for determining trust and impulse buying. Therefore, brands may consider inviting ICs for a live product review to enhance interaction, which can strengthen the IC-consumer bond and bring the ICs closer to consumers. Finally, this study provides a way for brands to utilize consumers' adoration toward ICs. Brands should manage to track the committed and motivated online followers of ICs and deliver targeted information to maximize the benefit.
This study also provides strategic guidance for ICs to foster trust in consumers and ensure effective enactment of endorsement presentation. Most importantly, ICs should be prudent in ensuring that the brands they choose to cooperate with can adequately represent their image, which is essential in maintaining trust. Since the perceived fit between the IC and the brand significantly influences consumers' trust toward the ICs, an inappropriate cooperation can be even worse for the IC's image than that of the brand. ICs are also encouraged to frequently create entertaining content and generate trending topics to maintain popularity and exert effective influence over consumers. In addition, ICs can consider openly sharing not only professional knowledge but also their everyday experiences and emotions to nurture IC-consumer closeness.
Since the phenomenon of the IC is common worldwide [108], our findings can also guide western marketers to cultivate ICs who enjoy high popularity and with whom consumers share common beliefs. However, while western culture emphasizes the values of independence and individuality, whether ICs with a large or small social distance from consumers should be employed still needs further investigation.

Limitations and Future Research
Several limitations and possible opportunities exist that should be addressed in future research. First, the fact that the participants were asked to imagine an IC recommending luxury fashion may have caused some cognitive burden for the participants. However, we have guaranteed the internal validity of the survey by checking that all the ICs selected were similar and all the luxury fashion had comparable prices and market positioning. Second, although trust has been discussed as the only, albeit significant, mediator between persuasion factors and purchase decisions, there may be other mediating variables such as brand equity [109] and para-social interaction [94] that could be analyzed and tested in the future. Third, as previous studies have investigated effective ways of fostering brand love in driving purchase intention [85,86], further research can introduce the similar concept of celebrity love as a new driver of impulse buying. Finally, the sample only represents China. Future research may want to extend our work to different geographic and cultural contexts.
Practically, while impulse buying is to some extent spontaneous, it may not lead to continuous repurchase. Further measures should be investigated to cultivate the adhesiveness of consumers. Increasingly lower entry barriers have facilitated a wide range of people becoming ICs, which may result in novel problems. Brand owners and researchers are faced with substantial challenges, requiring comprehensive consideration, in effectively deploying IC endorsement strategies.

Data Availability Statement:
The data presented in this study are available on request from the corresponding author.

Conflicts of Interest:
The authors declare no conflict of interest.