To this end, we take a document stream from Twitter and replace the message content of tweets nominally relating to a particular event (based on hashtag analysis) with distinct tweet-length mentions of events from the Topic Detection and Tracking corpus (TDT3) 3 dataset.
our datasets contain "background events" in the original Twitter document stream that we don't have annotations for, and "novel events" from TDT that we do have annotations for, and that form the basis of our evaluation.