Macro or Micro Influencer? A quantitative study examining the impact of source credibility on brand image and purchase intention comparing macro and micro influencers on Instagram

Based on the growth of social media many companies change their advertising strategy to online campaigns via online channels such as Facebook, Twitter, Snapchat or Instagram (Samat, Hashim and Yusoff, 2014; Mangold, Miller and Brockway, 2009). One of the major social media channels is Instagram which has been steadily growing (Statista, 2017a) and therefore grew in importance for businesses (Business Insider UK, 2016). Due to the increasing relevance of social media, companies shift from traditional celebrity endorsement to online influencer marketing, which creates opportunities to reach massive target audiences for product and brand promotions (Brandwatch, 2015). The effectiveness of celebrity endorsement has often been tested with Ohanian’s source credibility model (1990) and findings show that celebrities are more effective than non-celebrities when it comes to effects on e.g. brand image or purchase intention (e.g. Erdogan, 1999; Elberse and Verleun, 2012; Erdogan, Baker and Tagg, 2001; Dom, Ramli, Chin and Fern, 2016; Zamudio, 2016; Atkin and Block, 1983). The purpose of this paper is to test the effectiveness of influencers regarding brand image and purchase intention with the help of the source credibility model (Ohanian, 1990). As micro and macro influencers are the most common types of influencers based on their follower numbers, (e.g. Phillips, 2017; Schneider, 2017; Lee, 2016) this study aims to determine if the amount of followers matters when it comes to a relationship between source credibility and effects on brands. Findings were gathered with a sample of 196 respondents. The independent variables attrac-tiveness, expertise and trustworthiness as well as the dependent variables brand image and pur-chase intention were measured using existing scales. Correlation tests as well as simple linear regression tests were undertaken to measure the linear relationships of the variables (Allen and Bennet, 2014). Results show that an influencer’s attributes attractiveness, expertise and trustworthiness have strong effects on a brand’s image and a consumer’s buying decision. However, only marginal differences in effectiveness could be found comparing macro and micro influencers, which leads to the conclusion that the number of followers is not crucial to improve a brand’s image or create purchase intentions. Therefore, companies can save money choosing micro influencers while being effective regarding brand image and purchase intention