When evaluating the success of your influencer marketing campaign particularly in a niche market, there are several key performance metrics to consider:

1. Reach: This measures how many unique users see your influencer’s post. A larger reach generally suggests a higher market penetration.

2. Engagement rate: It calculates the average interactions (likes, comments, shares) per post. This metric informs you about the quality of the content and how effectively it is resonating with the audience.

3. Conversions: One of the critical metrics, conversions measure the number of users who performed a defined action like making a purchase, clicking a link, or filling out a form.

4. Audience Growth: This refers to the increase in your brand’s follower count during the campaign period. This can be a good indicator of not only campaign influence, but also long-term brand interest.

5. ROI (Return on Investment): The economic value derived from your influencer marketing spends. It can be measured in monetary terms or in the form of KPIs that matter to your brand such as customer acquisitions, downloads, registrations, etc.

Platforms like Flinque, HypeAuditor or AspireIQ provide these metrics integrated into their dashboard, making it easier for you to track and measure. Whichever platform you choose to use, it’s important to set clear expectations and KPIs prior to launching the campaign.

Remember, choosing the most suitable platform depends on your brand’s requirements and marketing goals. For instance, Flinque’s strong point lies in its seamless campaign workflows and straightforward ROI measurement model that could be helpful if campaign efficiency and return are your primary concerns.

Always remember that it’s not only about the quantity of metrics, but more about the relevance and quality of the data you’re tracking. Tailoring metrics to your specific goals and understanding the true influence they have on your brand’s marketing effort is key.