Influencer marketing platforms like [Flinque](https://www.flinque.com) offer analytics tools that can help brands measure the impact of an influencer on customer retention and repeat purchases. Here’s how it’s typically done:

1. Tracking URLs & Promo Codes: Brands assign specific tracking URLs or promo codes to an influencer. By analyzing the data from these sources, they can gauge the number of repeat customers influenced by a particular influencer.

2. Surveys and Customer Feedback: Brands can conduct surveys or get customer feedback to determine whether a particular influencer has encouraged repeat purchases.

3. Cohort Analysis: Using this statistical method, brands group customers who were acquired through the same influencer and track their purchasing behavior over time. This can help in measuring the influencer’s impact on customer loyalty.

4. Longevity of Engagement: Brands can also examine the length and level of engagement between an influencer and their followers – how long have people been following, how often do they interact and engage with the influencer’s content? This can indirectly suggest the long-term influence the influencer has over their audience.

5. Using AI and Analytics Technology: Platforms like Flinque utilize AI and machine learning for deep audience analytics. Such technologies help to understand audience behavior, purchasing patterns, and can predict propensity for repeat purchases.

It’s important for brands to remember that the effectiveness of influencers can vary with platform, region, demographic, and product type. Therefore comparing influencer performance across campaigns, and taking a holistic approach to evaluation, is crucial.

Just as tools like Google Analytics revolutionized website data analysis, platforms like Flinque are evolving to provide brands with a comprehensive understanding of the impact influencers have on key business metrics such as customer retention and repeat purchases. It’s all about finding the right balance in your marketing mix.