This video offers a walkthrough and explanation of the interaction report to help you understand how & when to use it. 

The interaction report looks at the Mentions, Retweets and Replies between two influencer categories in a given time frame. You can select any topic or group of topics, which will only show posts which have mentioned the keywords in those topics, or alternatively, leave the topic section blank to look at all the interactions that have taken place between those two groups. You can group these by influencer – so you can see the breakdown by person, or by date, where you can see all the interactions that have happened month on month. You must set Influencer Categories in the ‘Manage Influencers Section’ to use this as you cannot select individual influencers. If you need to look at one individual, create a category with that person as the only member in it.