The Effect of Brand Personality, Consumer and Endorser on the Effectiveness of Endorsement of Famous Athletes with the Approach of Congruence Theory

Introduction
In today’s globalized economy, the sports industry faces unprecedented challenges as manufacturers of sporting goods strive to achieve competitive advantage and sustain their presence in international markets  (Dwivedi et al, 2021). Social media (SM) platforms such as Facebook, Instagram, YouTube, and Twitter have rapidly become the preferred channels for brand communication and advertising (De Mooij, 2021). With their extensive reach, these platforms serve as vital spaces where businesses can promote products and engage with consumers. For instance, Nike has elevated social media marketing to new heights by cultivating an iconic brand image.
     The proliferation of social media and the growing influence of celebrity athletes have introduced new dynamics into sports marketing. The use of brand personality and athlete endorsers to promote health and fitness has emerged as a critical focus for marketers (Moreno et al, 2023). Research suggests that the effectiveness of brand associations with major sporting events like the Olympics may be mediated by brand personality traits, though the strength of these associations varies (Ahn & Kang, 2022).
   Modern consumers tend to shop at outlets offering a comprehensive range of sports products, making brand preference a decisive factor in purchasing behavior (Kelman, 2017). Brands have become invaluable intellectual assets that drive growth and revenue (Friedman & Friedman, 1979).
    Internet-based advertising, particularly via athlete endorsers, is now a cornerstone of sports marketing strategy, meriting rigorous investigation of its effectiveness (Till  & Busler, 2000).
 Brand personality fosters emotional connections between consumers and brands, resembling interpersonal relationships (Hung, 2014). With a saturated sports goods market, managers increasingly focus on enhancing brand personality to strengthen consumer-brand bonds (Abeza, et al, 2014).
    In Iran, the use of athlete endorsers has gained traction across industries. Examples include prominent figures like Ali Karimi (Arian Sazeh), Alireza Beiranvand (Pars Oil), and Behdad Salimi (Kalleh Products). However, little is known about how congruence between brand personality, endorsers, and consumers affects endorsement effectiveness. This study seeks to integrate these dimensions into a unified model and assess their impact on four key outcomes: brand awareness, brand attitude, behavioral intentions, and brand commitment.
 
Mothodology
This study employed a descriptive-correlational design with an applied purpose, conducted using a survey-based approach. The target population comprised consumers of products endorsed by prominent Iranian athletes, including Ali Karimi (Arian Sazeh, My Products), Alireza Beiranvand (Pars Oil, Flow Max
   Engine Oil), Mehdi Rahmati and Mehdi Mahdavikia (Mihan Products), Behdad Salimi (Kalleh Products), Seyed Mohammad Mousavi (Rexona Products), Pejman Jamshidi (Shahr Farsh), Ahmadreza Abedzadeh (KWC Faucets), and Mohammadreza Geraei (MVM Products).
    The sample size was estimated based on recommendations for partial least squares structural equation modeling (PLS-SEM), suggesting 10–20 times the number of parameters in the conceptual model. Given 22 latent variables in the model, a minimum sample size of 220 was required. Ultimately, 427 respondents were selected using a convenience sampling method. Data were collected via a structured questionnaire consisting of two sections. The first section captured demographic characteristics, while the second section measured core study variables using established scales. Brand personality, consumer personality, and endorser personality congruence were assessed using the scale developed by Sirgy et al. (1991), previously adapted in Aghazadeh et al. (2015). Congruence was calculated as:
Endorsement effectiveness was measured using four indicators: brand awareness (4 items; Escalas & Bettman, 2003), brand attitude (3 items; Park et al., 2010), brand commitment (5 items; Fullerton, 2005), and behavioral intentions (6 items; Park et al., 2010).
    All items employed a five-point Likert scale (1 = strongly disagree, 5 = strongly agree). Content and face validity were confirmed by a panel of 12 experts. Construct validity was assessed using confirmatory factor analysis (CFA), and reliability was verified with Cronbach’s alpha (α = 0.803), exceeding the recommended threshold of 0.70 (Nunnally & Bernstein, 1994). Data were analyzed using SPSS v24 for descriptive statistics and SmartPLS v4 for hypothesis testing via PLS-SEM (Ringle et al., 2023).
 
Fingdings
The demographic profile of the participants revealed that 40.7% were female and 59.3% male. The age distribution indicated that the largest proportion of respondents (32.7%, n=140) were under 20 years, whereas only 11% (n=47) were aged 51 years and above. Regarding educational attainment, 29.7% (n=127) held less than a high school diploma, while only 4.6% (n=20) reported holding an associate degree. In terms of income, 41.7% (n=178) earned less than 50 million IRR per month, whereas 19.9% (n=85) reported monthly earnings exceeding 100 million IRR.
    The structural equation modeling (SEM) process began with the evaluation of the measurement model using SmartPLS 4. All factor loadings exceeded the threshold of 0.50, with no items requiring removal based on Henseler et al. (2009). Reliability and convergent validity were assessed using four indices: Cronbach’s alpha, rho_A (Spearman’s reliability coefficient), composite reliability (CR), and average variance extracted (AVE). Table 1 summarizes these metrics.
All Cronbach’s alpha coefficients surpassed the recommended threshold of 0.70 (Nunnally & Bernstein, 1994). Similarly, rho_A values exceeded 0.60, meeting the criterion suggested
by Ringle et al. (2015). The composite reliability (CR) for all constructs was above 0.70, and the AVE values were all greater than 0.50, supporting convergent validity (Hair et al., 2021). Discriminant validity was assessed using the Fornell-Larcker criterion. Square roots of AVE values exceeded inter-construct correlations, indicating satisfactory discriminant validity. 
    The structural model was then evaluated. Moderator analyses examined the interaction effects of congruence variables. Results revealed that congruence between endorser personality and consumer personality significantly moderated the relationship between consumer personality and endorsement effectiveness (β=0.164, T=1.709, p<0.10). Similarly, congruence between brand and consumer personality had a significant moderating effect (β=0.528, T=9.725, p<0.001). However, no significant moderation was observed for congruence between brand and endorser personality on the paths examined.The model’s explanatory power was evaluated using R². According to Cohen (1998), R² values of 0.19, 0.33, and 0.67 indicate weak, moderate, and substantial effects, respectively.          
    The R² value of 0.529 for endorsement effectiveness suggests a moderate-to-strong explanatory power. The f² effect size showed that brand personality had the largest effect (f²=0.317).
    Predictive relevance (Q²) was assessed using the Stone-Geisser criterion, yielding values in the range of 0.15–0.32, indicating medium to high predictive relevance. Model fit was evaluated using the standardized root mean square residual (SRMR). The SRMR value of 0.0789 fell below the recommended threshold of 0.08 (Henseler et al., 2016), suggesting an acceptable model fit.
    These findings confirm the robustness of the measurement and structural models and support the hypothesized relationships and moderating effects, with some exceptions noted in the moderator analyses.
 
Discussion and Conclusion
The findings of this study confirmed that the endorser’s personality had a direct, positive, and significant impact on endorsement effectiveness. This aligns with Kelman’s (1961), conceptualization, which posits two underlying social processes for effective endorsements: identification and internalization. Identification suggests that consumers adopt the behaviors and recommendations of celebrities because of admiration and perceived affinity, while internalization reflects their belief in the validity of the endorsed attitudes or behaviors .Consequently, the successful selection of a celebrity endorser is not merely a tactical decision but a strategic one, which can shape consumer perceptions of brand personality and drive market growth. Friedman et al. (1979), further distinguish between two endorsement types: attractiveness-based endorsements, effective for low-involvement purchases, and expertise-based endorsements, which are more effective for high-involvement products. For instance, Michael Jordan’s endorsements of Nike products resonate more effectively with consumers due to congruence between his sports expertise and the product domain, compared to less relevant categories like telecommunications. Similarly, the present findings underscore the importance of aligning celebrity expertise with the endorsed product category to maximize credibility and consumer trust.
    Interestingly, the moderating effects of brand personality and consumer personality on endorsement effectiveness were not significant. This result suggests that congruence between brand, endorser, and consumer personalities-known as the "match-up hypothesis" may not uniformly enhance endorsement outcomes. However, Hong (2014) contends that perceptual fit between the celebrity and product enhances believability and consumer acceptance, indicating the need for further nuanced exploration of this relationship.
    The study also emphasizes the evolving role of celebrities in sports marketing in the digital era. Social media platforms such as Instagram, Twitter, and YouTube enable closer, more dynamic interactions between celebrities and their fans, thereby increasing the influence of endorsements. Du et al. (2015) reported that brands leveraging social media endorsements demonstrated stronger consumer-brand relationships, supporting our findings regarding emotional attachment to endorsers and the impact on consumer behavior.
Notably, this study found no significant effects of consumer personality on endorsement effectiveness via moderating variables. This indicates that consumers perceive endorsement effectiveness primarily when there is clear exposure to the celebrity and brand together. Moreover, the multidimensionality of athlete celebrity personalities-encompassing attractiveness, trustworthiness, and expertise-highlights their complex influence on consumer attitudes. Yet, as previous studies warn, missteps by celebrity endorsers, whether on or off the field, can severely damage brand image and credibility (18). Therefore, understanding consumer perceptions and responses to celebrity behavior is vital in developing resilient endorsement strategies.     For marketing managers in the sports industry, these findings suggest the importance of strategic alignment between celebrity endorsers, brand personality, and target consumer profiles. Endorsement strategies should integrate celebrity selection with media strategy, creative alignment, and audience profiling to enhance effectiveness. Furthermore, managers must consider the potential risks of celebrity misbehavior and design contingency plans to safeguard brand equity. In culturally diverse markets like Iran, where demographic dynamics vary significantly, careful management of endorser-brand fit is crucial for optimizing endorsement outcomes.
    This study contributes to endorsement literature by integrating multidimensional personality congruence into a single framework, offering a comprehensive model for understanding and managing celebrity endorsement effectiveness in sports marketing.