The Effects of Celebrity Endorsement on Customer’s Attitude toward Brand and Purchase Intention

Celebrity endorsement has become a popular choice in advertising due to the its originality and the celebrity’s attractiveness that make a big impact on brand awareness and customer behavior. This study analyzes the effect of celebrity endorsement on customer’s attitude toward brand as well as the effect of customer’s attitude toward brand on customer’s purchase intention in Vietnam. A survey was conducted with 306 individuals in Vietnam. After conducting the explanatory factor analysis (EFA), and multi-variable regression analysis, results indicate that customer’s attitude toward brand is positively affected by 03 factors: celebrity match-up congruence with the brand/product, celebrity trustworthiness, and celebrity expertise. Attitude toward brand also has a positive impact on customer’s purchase intention.


Introduction
In recent years, the development of commercial communication and of rise-up of live TV shows has attracted lots of attention from the public, especially young generation. Marketing strategies of companies focus mostly on promoting products to the market with core objectives as to persuade their customers; since the customers have got a lot of knowledge, references, and choices before making a purchase decision, competition has also became more severely. There are a number of ways to promote brands, but employing celebrity as an aid to the brand has become popular in all over the world (Friedman et al., 1979;Kamins, 1989). This is because advertisements in which celebrity appears are generating effective outcomes in making the brand identity and retaining customers' attention, that is the mandatory objective of any commerce (Erdogan, 1999;Kamins & Gupta, 1994;Kaikati, 1987;Patti & Frazer, 1988). Belch and Belch (2004, p. 174) showed that "in today's television viewing environment and the "stopping power" of celebrity endorsed commercials are more remarkable". However, if they later make up a negative image of themselves, brand image will also be affected. Therefore, it is very important to select appropriate celebrity to represent a brand.
There have been a lot of studies in the world on the effect of celebrity on brand promotion activities, but this field hasn't been addressed adequately in Vietnam. The questions are that which factors of celebrity endorsement will have effect on customer's attitude toward brand and how is the relationship between customer's attitude toward brand and purchase intention in Vietnam? 310): "An individual who enjoys public recognition and who uses this recognition on behalf of a customer good by appearing with it in an advertisement". According to Kotler et al. (2007), celebrity endorsement is one of communication channels that are used by celebrity as a means of expressing their words to promote the brand on basis of their fame and personalities.

Meaning Transfer Model
According to McCracken (1989), this model is developed to illustrate celebrity endorsement process. Advertising is one of means to transfer individual meaning to the brands. This model is divided into three stages. First stage is the development of celebrity image and description of cultural meaning of the society. In this stage, it is assessed whether subject, people and context are suitable to the celebrity. The second stage is relevant to the celebrity's transfer of meanings from brand endorsement to the product. In the final stage, brand image is transferred to the customers. Path of meaning movement. Stage of meaning movement. Source: McCracken, 1989, p. 45.

Customer's Attitude Toward Brand
Customer's attitude toward brand is predisposition that focuses on favorable or unfavorable impact on a specific brand after watching an advertisement on that brand (Phelps & Hoy, 1996). According to Lutz et al. (1983), customer's attitude toward brand is the customer's emotional reaction toward a brand advertisement. It is associated with the customer's feeling if his/her purchase intention toward the brand is positive or negative, favorable or unfavorable.

The Elaboration Likelihood Model (ELM)
Elaboration Likelihood Model (ELM) is a model that consists of two phases of response toward advertising incentive. It explains how attitudes are formed on basis of the degree of participation. Current attitude may be changed and it is assumed that when a customer receives a message, he starts processing it. There are two possible directions: Central route used for persuasion if customer participation is high, or peripheral route used for persuasion if customer participation is low. The model has two fundamental factors, motivation and ability to process communication. Motivation means the customer's readiness, participation, and needs. Ability means the knowledge, qualification, and capacity to process information (Petty et al., 1983).

The Relation between Source Credibility Model and Customer's Attitude toward Brand
Hovland & Weiss (1953) introduced a source credibility model, which is further studied by Ohanian (1990) (cited by Armando, 2014). According to source credibility model, "the effectiveness of a message depends on the apparent level of expertise and trustworthiness of the endorser" (Hovland & Weiss, 1953, p. 20) 2.4.1 Celebrity Trustworthiness Trustworthiness refers to "the honesty, integrity and believability of an endorser" (Erdogan et al., 2001, p. 40). A celebrity is considered as trustworthy (Goldsmith et al., 2000) and his/her trustworthiness is described as a summary of values that create positive features and increase the acceptance of the message (Erdogan, 1999). Trustworthiness is the most useful and effective tool to make the customer be more confident and reliable on the brand (Ohanian, 1990). A hypothesis is provided: Hypothesis 1 (H1): The more celebrity trustworthiness is perceived by the customer, the more positive customer's attitude toward brand will be. Hovland et al. (1953) defines expertise as the level of knowledge and experience that a person may obtain in a specific field that is acknowledged as valid. The more persuasive a celebrity's expertise is (Aaker, 1997), the more purchase decisions will be generated (Ohanian, 1991). Speck, Schumann, and Thompson (1988) affirms that celebrity is considered as an expert in a specific field, resulting in a higher brand endorsement than a celebrity without expertise (Hoekman & Bosmans, 2010). Following hypothesis is provided:

Celebrity Expertise
Hypothesis 2 (H2): The more celebrity expertise is perceived by the customer, the more positive customer's attitude toward brand will be.

The Relation between Source Attractiveness Model and Customer's Attitude toward Brand
Source attractiveness model is developed by McGuire (1985), he holds that an individual message is accepted and affected by the similarity between the receiver and the sender together with the familiarity and likeliness. The meaning of source attractiveness model is referenced to be a famous philosopher, Aristotle: "beauty is a greater recommendation than any letter of introduction". Aristotle wants to emphasize that the most importance is beauty and attractiveness (Hoekman & Bosmans, 2010).

Celebrity Attractiveness
Physical attractiveness transited via a person's weight, height, and facial beauty is the very first expressions perceived by another (Bardia et al., 2011). This concept does not only means physical attractiveness. It also requires mental skills, personality, lifestyle, and art talents (Erdogan, 1999). A celebrity is attractive because he/she has built up a popular image among the public. His/her attractiveness increases the persuasiveness toward the customers as they want to be like the celebrity that they love (Cohen & Golden, 1972). A hypothesis is given Hypothesis 3 (H3): The more celebrity attractiveness is perceived by the customer, the more positive customer's attitude toward brand will be.

Celebrity Similarity
Similarity is described as "a supposed resemblance between the source and the receiver of the message" (McGuire, 1985). In other words, a customer may similarize himself with the endorser. People will be more easily influenced when they find the similarity between them and the endorser. If the celebrity and the customers share popular factors, such as similar interest or lifestyle, a better association will be formed (Erdogan, 1999). Following hypothesis is provided: Hypothesis 4 (H4): The more celebrity similarity is perceived by the customer, the more positive customer's attitude toward brand will be.

Celebrity Liking
Likeability is the "affection for the source as a result of the source's physical appearance and behaviour" (McGuire, 1985, p. 239). In addition, McGuire also holds that when customers like a celebrity, they will like brands associated with the celebrity. A hypothesis is provided: Hypothesis 5 (H5): The more celebrity liking is perceived by the customer, the more positive customer's attitude toward brand will be.

Celebrity Familiarity
Familiarity means the feeling of similarity by means of emotions and contact with a celebrity (Erdogan, 1999; ijef.ccsenet.org International Journal of Economics and Finance Vol. 9, No. 1; 2017 Belch & Belch, 2004). Celebrity familiarity will have a more positive impact when the customer himself finds that he/she is similar to the celebrity. This is called the mere exposure effect (Zajonc, 1968). When the customers have short contacts with the celebrity and contact interval becomes longer, the effects of familiarity will improve customer's attitude toward brand. On the contrary, the effect is negative when they have long contacts and contact interval becomes shorter (Bornstein, 1989). A hypothesis is given by: Hypothesis 6 (H6): The more celebrity familiarity is perceived by the customer, the more positive customer's attitude toward brand will be.

The Relationship between Brand/Product Matchup Hypothesis Model and Customer's Attitude toward Brand
According to Forkan (1980); Kamins (1989), brand/product matchup hypothesis model means that celebrity image and product message must be similar and matched up in order for the advertisement to be effective.

Celebrity Match-up Congruence With The Brand/Product
A number of studies conducted by Cooper (1984) and Forkan (1980) indicate that celebrity match-up congruence with the brand/product has a significant play. When a product is advertised by a celebrity with suitable image that is highly relevant to the product, the confidence will be higher on the advertisement and the celebrity compared to a product image promoted by a less famous, less relevant person (Kotler, 1997). A hypothesis is given: Hypothesis 7 (H7): The more celebrity match-up congruence with the brand/product is perceived by the customer, the more positive customer's attitude toward brand will be.

The Relationship between Customer's Attitude toward Brand and Purchase Intention
Customer's purchase intention addresses the predisposition to purchase a certain brand or product (Belch & Belch, 2004). Purchase intention also tells about the possibility that a person will purchase a product (Phelps & Hoy, 1996). Amos, et al. (2008) hold that the customer's positive attitude toward celebrity endorsement will improve his/her purchase intention. Many studies also indicate that customer's attitude toward brand has a positive and significant impact on purchase intention (Mitchell & Olson, 1981;Gresham & Shimp, 1985;Batra & Ray, 1986;Phelps & Hoy, 1996). A hypothesis is provided: Hypothesis 8 (H8): The more positive customer's attitude toward brand is, the more positive purchase intention will be.

Methodology
This study is conducted in two major stages. A qualitative study is conducted by face-to-face direct interview on 04 marketing experts and a group discussion is carried out among 12 customers of 18 years old or more, which is intended to modify, supplement, and complete the measurement scale. A quantitative study is carried out to collect data by using a questionnaire survey based on Likert rating scale with 5 options, including "1-Totally Disagree", "2-Disagree", "3-Neutral", "4-Agree", "5-Totally Agree", used to measure observation variables for each factor.

Proposed Research Model
From theories and previous studies, an analysis is conducted on the effect of the celebrity endorsement consisting of 07 factors, which are: celebrity trustworthiness, celebrity attractiveness, celebrity expertise, celebrity similarity, celebrity liking, celebrity familiarity, celebrity match-up congruence with the brand/product are independent varieties. Customer's attitude toward brand means temporary variable. Purchase intention means dependent variable. ijef.ccsenet.org International Journal of Economics and Finance Vol. 9, No. 1; 2017 Figure 3. Proposed research model

Research Data
A total of 534 questionnaire sheets were directly distributed to the customers of 18 years old or more in Vietnam or via online method. A total of 392 sheets were returned and, after being screened, 306 sheets were valid for data analysis, achieving a ratio of 78.06% compared to actual data.

Descritptive Statistics by Characteristics
For gender, there are 184 female and 122 male respondents, accounting for 60.1% and 39.9%, respectively, of which 61.4% are single, 38.6% are married. For age, respondents of 18-25 years old account for 28.1%, of 26-35 years old account for 58.5%, 36-45 years old account for 7.5%, and of more than 45 years old account for 5.9%. For education, university respondents account for 45.1%, post-graduate ones account for 28.4%, primary school ones account for 2.6%, secondary school ones account for 7.2%, high school ones account for 8.5%, and college-intermediary school ones account for 8.2%. Purchase intention: PI5 is eliminated because it has the Cronbach's Alpha if item deleted is 0.865, which is higher than the Cronbach's Alpha coefficient of the 1st scale test value of 0.860. In the 2nd test, the Cronbach's Alpha coefficient is 0.865, and item-total correlation for all variables are satisfied (higher than 0.3). Therefore, remaining 4 observation variables are included in EFA.

Explanatory Factor Analysis (EFA)
Explanatory factor analysis is conducted on whether celebrity endorsement has an impact on customer 's attitude toward brand. After the 1st analysis, CA1, CA2, CL1, CL3 CL7, CL2, CL5, CE1, CF4, CL6, CL4 are eliminated. After the 2nd analysis, CA6, CA7, CE4 are eliminated. After 3 nd analysis, CF5 and CF7 are eliminated. After 4 th analysis, factor loading values are satisfactory with KMO coefficient of 0.844 with significance level of the Bartlett test of 0.000. Based on results presented in Table 3, 18 observation variables are satisfactory and divided into 6 factor groups.

Regression Analysis
According to results in Table 4, Analysis of the fitness of the regression model on customer's attitude toward brand, Adjusted R 2 get value is 0.273, which is varied by 27.3% in term of "customer's attitude toward brand", it can be explained by independent factors in the model. F = 20.058 with significant level of 0.000. Therefore, the regression model is considered as overall fit. According to the Table 5, the match-up congruence of the regression model of purchase intention, Adjusted R 2 get value is 0.483, means 48.3% upon the variability of the purchase intention can be explained by the customers' ijef.ccsenet.org International Journal of Economics and Finance Vol. 9, No. 1; 2017 attitude towards brand. F = 285.814 with significant level of 0.000; therefore, the regression model is considered as overall fit.

Celebrity Trustworthiness
This variable is statistically significant at 1%, with value  = 0.206> 0, this means that H1 hypothesis is supported. Trustworthiness refers to "the honesty, integrity and believability of an endorser" (Erdogan et al., 2001). The celebrity is considered as a trustworthy person (Goldsmith et al., 2000). A study by Pham & Nguyen (2015) indicates that "celebrity trustworthiness" has a positive impact on "customer's attitude toward the advertisement". Results of this study also find positive impact of "celebrity trustworthiness" on "customer's attitude toward brand". This can be explained as follows: celebrity appearance in commerces in Vietnam has become popular because the celebrity can influence the public. However, "scandals" in their personal lives have caused the public wonder and lose trusts in the celebrity's ethics. Only a few celebrities are acknowledged for their talents and ethics, and they are respected and relied upon by most of the public and colleagues. Therefore, celebrity endorsement will have more impact on the customers than non-celebrity trustworthy.

Celebrity Expertise
This factor is statistically significant at 1%, with value  = 0.181> 0, this means that H2 hypothesis is supported. The expertise mentions the level of knowledge and experience that a person may obtain in a specific field that is acknowledged as valid (Hovland et al., 1953). The more persuasive a celebrity's expertise is (Aaker, 1997), the more purchase decisions will be generated (Ohanian, 1991). A study by Pham and Nguyen (2015) indicates that "celebrity expertise" has a positive impact on "customer's attitude toward the advertisement". Results of this study also find positive impact of "celebrity expertise" on "customer's attitude toward brand". This can be explained as follows: With their attractiveness and influencing ability, celebrities are highly paid for their appearance in advertisements although the brand is not related to their expertises. Therefore, customers feel that they are not assured, and their confidence in the brand is wondered. So, enterprises need to select the celebrities that have expertises related to the brand to be advertised so that customers will be more confident and accept it more positively.

Celebrity Attractiveness
This variable is statistically significant at 5%, with value  = 0.038, this means that H3 hypothesis is not supported. A study by Pham & Nguyen (2015) indicates that "celebrity attractiveness" has a positive impact on "customer's attitude toward the advertisement". However, this study only considers the "customers' attitude towards brand" and the its results indicate no positive effect of the "celebrity attractiveness" factor on the "customer's attitude toward brand". This can be explained as follows: Most of today's celebrities have pretty, attractive and ideal appearance to make their advertisements more impressive. Therefore, celebrity attractiveness will generate attention toward the customers and make advertisements more attractive, however, attractiveness has no impact on customer's attitude toward brand.

Celebrity Similarity
This factor is statistically significant at 5%, with value  = 0.052, this means that H4 hypothesis is not supported. A study by Pham and Nguyen (2015) indicates that "celebrity similarity" has a positive impact on "customer's attitude toward the advertisement". However, this study only considers the "customers' attitude towards brand" ijef.ccsenet.org International Journal of Economics and Finance Vol. 9, No. 1;2017 and the its results indicate no positive effect of the "celebrity similarity" factor on the "customer's attitude toward brand". This can be explained as follows: Celebrities have ideal appearance and outstanding talents. All fans want to become like the ones that they like, from their lifestyle, likings, fashion style, etc. They learn after celebrities and think that they share similar values, to a certain extent, with celebrities. However, similarity only makes advertisements with celebrity endorsement receive more attention and be remembered, but it does not affect customer's attitude toward brand.

Celebrity Familiarity
This variable is statistically significant at 5%, with value  = 0.003, meaning that H'5 hypothesis is not supported. The study by Pham and Nguyen (2015) does not consider "celebrity familiarity" factor. A study by Shahrokh and Arefi (2013) indicates that there is a positive impact of "celebrity familiarity" on "source attractiveness model", and thereby resulting in a positive impact on "the effectiveness of celebrity endorsement". However, this study only considers the "customers' attitude towards brand" and the its results indicate no positive effect of the "celebrity familiarity" factor on the "customer's attitude toward brand". This can be explained as follows: This celebrity will be covered everywhere so that customers can easily see the ones they love just by clicking or navigating a remote control. It is celebrity familiarity that will help the customers easily memorize and be impressed at the advertisements with celebrity endorsement, but familiarity has no impact on customer's attitude toward brand.

Celebrity Match-up Congruence with The Brand/Product
This factor is statistically significant at 1%, with value  = 0.288 > 0, meaning that H'6 hypothesis is not supported. Celebrity match-up congruence with the brand / product may create the absolute confidence through the homogeneous process (Langmeyer & Walker, 1991), and cause positive effect on the customers' attitude towards advertisment, brand / product and purchase intention (Kirmani & Shiv, 1998). A study by Pham and Nguyen (2015) indicates that "celebrity match-up congruence with the brand / product" has a positive impact on "customer's attitude toward the advertisement". Results of this study also find positive impact of "celebrity match-up congruence with the brand / product" on "customer's attitude toward brand". This can be explained as follows: everyday, customers can watch a lots of advertisements with celebrity, even the same one in different advertisements. When a brand / product is advertised by a celebrity with suitable image that is highly relevant to the brand / product, the confidence will be higher on the advertisement and the celebrity compared to a brand / product image promoted by a less famous, less relevant person.

Customer's Attitude toward Brand
This variable is statistically significant at 1%, with value  = 0.696 > 0, meaning that H'7 hypothesis is not supported. Customer's attitude toward brand is predisposition that focuses on favorable or unfavorable impact on a specific brand after watching an advertisement on that brand (Phelps & Hoy, 1996). The study by Pham and Nguyen (2015) does not consider the effect of "customer's attitude toward brand" factor on the "purchase intention". Studies of Qurat and Mahira (2012), Aycha and Kaouther (2010) and Mazzini et al. (2014) indicate the positive effect of "customer's attitude toward brand" factor on the "purchase intention". Results of this study also affirm the correctness of previous studies. This impact is positive and considerable in Vietnamese market. Attitude is used as factor to forecast customer's intention and behavior (Fishbien & Ajzen, 1975;Ajzen, 1991). When customers have more positive attitude toward brand, they will more likely intend to purchase the products.

Conclusions
The final study model includes 7 factors of celebrity endorsement with impact on customer's attitude toward brand. Also, factors of attitude toward brand have impacts on customer's purchase intention. After testing the reliability of the measurement scale and conducting explanatory factor analysis, results are that celebrity liking factor is eliminated while other factors are retained, resulting in a correction of study model hypotheses. Results of the multi-variable regression analysis indicate that customer's attitude toward brand in Vietnam is positively affected by 03 factors: celebrity match-up congruence with the brand / product, celebrity trustworthiness, and celebrity expertises. Results also indicate that purchase intention is strongly and positively impacted by customer's attitude toward brand.

Suggestions of Policy Implications
Based on findings, the study suggests some policy implications as follows: Firstly, enterprises should pay careful attention to selecting celebrities for promoting the brand. If the celebrity ijef.ccsenet.org International Journal of Economics and Finance Vol. 9, No. 1; 2017 has made any dispute statement, improper behavior, and a negative scandal, it will negatively affect the brand and reputation of the enterprises. Therefore, it is necessary to select a trustworthy celebrity that is trusted by the public.
Secondly, not every celebrity endorses a brand that is within his/her expertise. Therefore, customers usually wonder that celebrity endorsement is just intended to make the ads attractive, but product quality is not persuasive because it is beyond his/her expertise. Thus, if an enterprise luckily chooses a celebrity that is an expert in the brand that it wants to promote, the persuasiveness and customer's attitude toward brand will be more positively impacted.
Thirdly, when enterprises can formulate a meaningful message that is suitable to the celebrity and brand, this will have a positive impact on customer's attitude toward brand. So, enterprises need to select a suitable celebrity for their brand images and advertising message that they want to transfer, so that customers have better perception of the advertisements and positive attitude toward the brand.