The best F-measure (82.82%) for the full text articles is achieved by using all the feature types except the co-occurring keywords.
"appear" is a real speculation keyword in 86% of its occurrences in the abstracts and in 83% of its occurrences in the full papers, whereas "can" is a real speculation keyword in 12% of its occurrences in the abstracts and in 16% of its occurrences in the full papers.