  We propose a dataset for event coreference resolution, which is based on
random samples drawn from multiple sources, languages, and countries. Early
scholarship on event information collection has not quantified the contribution
of event coreference resolution. We prepared and analyzed a representative
multilingual corpus and measured the performance and contribution of the
state-of-the-art event coreference resolution approaches. We found that almost
half of the event mentions in documents co-occur with other event mentions and
this makes it inevitable to obtain erroneous or partial event information. We
showed that event coreference resolution could help improving this situation.
Our contribution sheds light on a challenge that has been overlooked or hard to
study to date. Future event information collection studies can be designed
based on the results we present in this report. The repository for this study
is on https://github.com/emerging-welfare/ECR4-Contentious-Politics.
