We analyzed a tweet dataset which includes 326,747 posts (Details are given in Section 3) collected during 2011 London Riots, and result reveals that at least 18.91% of these tweets bear uncertainty characteristics 1 .
distinguishing uncertain statements from factual ones is crucial for users to synthesize social media information to produce or derive reliable interpretations, and this is expected helpful for applications like credibility analysis (Castillo et al., 2011) and rumor detection (Qazvinian et al., 2011) based on social media.