When does endorsement work? The moderating role of endorser and message characteristics

Purpose This study explores how both endorser and message characteristics moderate the effectiveness of influencer endorsements. Design/methodology/approach We adopted a quasi-experimental design to track endorsement events on social media and corresponding sales data from e-commerce platforms. Difference-in-difference (DID) models and regression analysis were used to examine the effects of celebrity endorsements and the moderating effects of various endorser and message characteristics. Findings We find that only influencers with over 10,000 followers significantly drive sales. Additionally, frequent endorsements by the same influencer are less effective. In terms of message characteristics, imagery and overt endorsements are found to be more effective than their text-only and subtle counterparts. Practical implications On average, influencers with less than 10,000 followers are unlikely to drive significant sales. Influencers need to be more strategic in their endorsement activities, as frequent endorsements can be detrimental. Overt and imagery endorsement messages are more effective than covert and text-only ones. Originality/value This study contributes to the influencer marketing literature by revealing the role of endorser and message characteristics in influencing the effectiveness of online influencer endorsements, and by quantifying the impact of online influencer endorsements on actual sales.