Annotation of subtitle paraphrases using a new web tool

This paper analyzes the manual annotation effort carried out to produce Opusparcus, the Open Subtitles Paraphrase Corpus for six European languages. Within the scope of the project, a new web-based annotation tool was created. We discuss the design choices behind the tool as well as the setup of the annotation task. We also evaluate the annotations obtained. Two independent annotators needed to decide to what extent two sentences approximately meant the same thing. The sentences originate from subtitles from movies and TV shows, which constitutes an interesting genre of mostly colloquial language. Inter-annotator agreement was found to be on par with a well-known previous paraphrase resource from the news domain, the Microsoft Research Paraphrase Corpus (MSRPC). Our annotation tool is open source. The tool can be used for closed projects with restricted access and controlled user authentification as well as open crowdsourced projects, in which anyone can participate and user identification takes place based on IP addresses.