Meta‐analysis of social media influencer impact: Key antecedents and theoretical foundations

This meta-analytic review offers a comprehensive framework for studying social media influencers by integrating multiple theoretical perspectives and measures. It analyzes 250 effect sizes from 53 studies, highlighting the significance of credibility, trustworthiness, and perceived expertise of social media influencers in shaping attitudinal outcomes. Source Credibility Theory emerges as the most robust explanatory framework, while Parasocial Interaction Theory and Congruity Theory also play essential roles. For behavioral outcomes, Source Credibility Theory and Congruity Theory remain influential, with moderate effects observed for homophily and variables from the two-step flow model. Methodological diversity, geographical context, platform context, product context, and influencer type contribute to variations in effect sizes. These findings provide insights into social media influencer influence dynamics and guide future research. Moreover, they contribute to theory development by shedding light on the mechanisms and conditions underlying social media influencer influence on consumer attitudes and behaviors.