Great answere form Quora.
This question could be answered a million different ways! In the world of influencer marketing, keep these considerations in mind: Consider the format: The content format that an influencer uses plays a large role in engagement. For example, the number of likes and comments are almost always lower for videos than photos. This is largely because a video view is a form of engagement in itself— a like or comment being a secondary level of activity.
Read the comments: The number of comments on a post should obviously be considered while measuring engagement. With that said, just because an influencer has dozens and dozens of comments on a photo doesn’t always mean that their content is well-received within their audience. If you look more closely at the type of comments being posted, they’ll often lack personalization by making generic blanket statements, such as “nice shot” or a range of random emojis. Commenting on posts has become a tactic many use to get their own account noticed by others. If you want to accurately measure authentic engagement, look to also find genuine feedback pertaining to the specific post. For example, if the image is about a hair-care product, authentic comments will often include consideration questions, such as if the influencer enjoyed using the product compared to a competitor. Measure with incentives: Brands will often provide influencers with a unique code to share with their audience that serves as a direct form of measurement for the effectiveness of that campaign. […]