Current Limitations in Cyberbullying Detection: on Evaluation Criteria, Reproducibility, and Data Scarcity

Chris Emmery*, Ben Verhoeven, Guy De Pauw, Gilles Jacobs, Cynthia Van Hee, Els Lefever, Bart Desmet, Véronique Hoste, Walter Daelemans

*Corresponding author for this work

Research output: Contribution to journalArticleScientific


The detection of online cyberbullying has seen an increase in societal importance, popularity in research, and available open data. Nevertheless, while computational power and affordability of resources continue to increase, the access restrictions on high-quality data limit the applicability of state-of-the-art techniques. Consequently, much of the recent research uses small, heterogeneous datasets, without a thorough evaluation of applicability. In this paper, we further illustrate these issues, as we (i) evaluate many publicly available resources for this task and demonstrate difficulties with data collection. These predominantly yield small datasets that fail to capture the required complex social dynamics and impede direct comparison of progress. We (ii) conduct an extensive set of experiments that indicate a general lack of cross-domain generalization of classifiers trained on these sources, and openly provide this framework to replicate and extend our evaluation criteria. Finally, we (iii) present an effective crowdsourcing method: simulating real-life bullying scenarios in a lab setting generates plausible data that can be effectively used to enrich real data. This largely circumvents the restrictions on data that can be collected, and increases classifier performance. We believe these contributions can aid in improving the empirical practices of future research in the field.
Original languageEnglish
Number of pages26
Publication statusE-pub ahead of print - 25 Oct 2019



  • cyberbullying detection
  • cybersecurity
  • machine learning
  • benchmarking
  • resource evaluation
  • cross-domain
  • reproducibility
  • crowdsourcing

Cite this

Emmery, C., Verhoeven, B., De Pauw, G., Jacobs, G., Van Hee, C., Lefever, E., ... Daelemans, W. (2019). Current Limitations in Cyberbullying Detection: on Evaluation Criteria, Reproducibility, and Data Scarcity. arXiv.