Good KPI, Good Influencer?

The question of how the impact of social media communication can be measured is a prominent topic in social media research, for example in terms of virality of content or the influence an individual has on others. While this is of interest in many different contexts, companies currently face this issue from a business perspective with the rise of influencer marketing. One of the most pressing questions in this field is how to measure success. Quantitative success metrics (e.g., number of likes) are mostly readily available and also predominantly used by both influencers themselves and companies. Still, it remains unclear what value these metrics actually have for influencer marketing and whether they are an appropriate proxy for the quality of the content. This is of special interest, as companies have only limited control over the content posted by influencers. We contribute to this area of research by combining secondary data on influencer marketing campaigns from Instagram with an online survey among marketing professionals. We find that in general, professionals consider an influencer's reach and their number of interactions as the most important success metrics. In contrast, when professionals are facing a trade-off between multiple metrics, they predominantly rely on the sentiment of user comments. We run a regression analysis showing that only the sentiment measure is positively related to the professional evaluation of the content, thus questioning the use of common quantitative metrics to evaluate social media influencers.