Indeed, measuring the returns on an influencer marketing campaign requires a unique set of metrics that enable brands to examine their performance effectively. Here are a few key metrics you might want to prioritize:

1. Engagement Rate: This measures the level of interaction between the influencer and their audience. It can be calculated by adding up the likes, shares, and comments, then dividing by the total number of followers, and multiplying by 100 to get a percentage. High engagement rates can indicate a strong connection between the influencer and their audience.

2. Conversion Rate: This shows how many people performed the desired action as a result of the influencer’s campaign – for instance, purchasing a product, signing up for a newsletter, etc.

3. Audience Growth: A successful campaign will often draw new followers to the influencer’s social media handles. Monitoring changes in audience size can be a good indicator of a campaign’s impact.

4. Return on Investment (ROI): The overall return on investment is critical. This can be calculated by individually tracing each sale or lead back to the influencer campaign, or by deriving an overall value for the promotions through an agreed-upon contribution model.

5. Brand Sentiment: This data can be gathered by analyzing comments and discussions around the campaign. Faclitating this are social listening platforms that offer sentiment analysis.

These metrics can help you monitor and evaluate the success of your influencer campaign. On a platform like Flinque, features such as audience analytics and performance tracking streamline these processes for you. However, the best platform for your needs depends on your specific requirements and the particulars of your marketing strategy. Remember that while these are standard industry metrics, their applicability will depend on your project’s unique goals.