Understanding the Role of Follower Size in Influencer Marketing: Examining the Perspective of Source Credibility and Attribution Theory

Applying source credibility and attribution theory as a theoretical framework, this study aims to find the role of follower size on the success of influencer marketing, along with the mediating impacts of source trustworthiness and influencers' motives and the moderating roles of source expertise and product types. A 4 (follower size: nano vs. micro vs. macro vs. mega) × 2 (source expertise: high vs. low) × 3 (product type: search vs. experience vs. credence) between-subjects design was employed. Data from an online experiment showed that the follower size leads to both the perception of source trustworthiness and extrinsic motive of influencers. When influencers are perceived as experts, it enhanced the effect of source trustworthiness on purchase intention and discounted the effect of follower size on consumers' attribution to extrinsic motive. Further, the product type moderated the role of source expertise on purchase intention. Theoretical and managerial implications are discussed.