Finding Eyewitness Tweets During Crises
Table 3: Individual feature class performance compared to the top three performing feature class combinations from each data set. For the top performing combinations, “CS” refers to the Crisis Sensitive feature class; “—” indicates that this was not a top performing combination for that data set.
['[BOLD] Individual Feature Performance', '[BOLD] Boston Bombing  [BOLD] Prec.', '[BOLD] Boston Bombing  [BOLD] Recall', '[BOLD] Boston Bombing  [BOLD] F1', '[BOLD] Hurricane Sandy  [BOLD] Prec.', '[BOLD] Hurricane Sandy  [BOLD] Recall', '[BOLD] Hurricane Sandy  [BOLD] F1']
To analyze how each feature class contributes to the task, we test each class individually. We find that word unigrams and bigrams obtain the highest scores in both crises. We also notice that our crisis-sensitive features do not perform in either of the crises by themselves. While looking at the individual feature classes provides an understanding of each individual class’s contribution to the problem, individual feature classes may combine for results that are superior to any one class alone. We find the top feature class combinations by assessing the F1-score of all ∑6i=1(6i)=63 possible combinations.