  Despite the importance of understanding causality, corpora addressing causal
relations are limited. There is a discrepancy between existing annotation
guidelines of event causality and conventional causality corpora that focus
more on linguistics. Many guidelines restrict themselves to include only
explicit relations or clause-based arguments. Therefore, we propose an
annotation schema for event causality that addresses these concerns. We
annotated 3,559 event sentences from protest event news with labels on whether
it contains causal relations or not. Our corpus is known as the Causal News
Corpus (CNC). A neural network built upon a state-of-the-art pre-trained
language model performed well with 81.20% F1 score on test set, and 83.46% in
5-folds cross-validation. CNC is transferable across two external corpora:
CausalTimeBank (CTB) and Penn Discourse Treebank (PDTB). Leveraging each of
these external datasets for training, we achieved up to approximately 64% F1 on
the CNC test set without additional fine-tuning. CNC also served as an
effective training and pre-training dataset for the two external corpora.
Lastly, we demonstrate the difficulty of our task to the layman in a
crowd-sourced annotation exercise. Our annotated corpus is publicly available,
providing a valuable resource for causal text mining researchers.
