Does Terrorism Trigger Online Hate Speech? On the Association of Events and Time Series
This work addresses the challenge of linking offline events to online behavior for researchers and policymakers interested in hate speech dynamics, but it appears incremental as it builds on existing event coincidence analysis frameworks.
The authors tackled the problem of measuring whether offline extreme events, like terrorist attacks, systematically trigger bursts of online hate speech by proposing a novel statistical method to analyze the association between sparse event series and time series peaks. They applied this method to show that Islamist terrorist attacks in Western Europe and North America are associated with increased hate speech and counter-hate speech on Twitter, though no specific numerical results are provided in the abstract.
Hate speech is ubiquitous on the Web. Recently, the offline causes that contribute to online hate speech have received increasing attention. A recurring question is whether the occurrence of extreme events offline systematically triggers bursts of hate speech online, indicated by peaks in the volume of hateful social media posts. Formally, this question translates into measuring the association between a sparse event series and a time series. We propose a novel statistical methodology to measure, test and visualize the systematic association between rare events and peaks in a time series. In contrast to previous methods for causal inference or independence tests on time series, our approach focuses only on the timing of events and peaks, and no other distributional characteristics. We follow the framework of event coincidence analysis (ECA) that was originally developed to correlate point processes. We formulate a discrete-time variant of ECA and derive all required distributions to enable analyses of peaks in time series, with a special focus on serial dependencies and peaks over multiple thresholds. The analysis gives rise to a novel visualization of the association via quantile-trigger rate plots. We demonstrate the utility of our approach by analyzing whether Islamist terrorist attacks in Western Europe and North America systematically trigger bursts of hate speech and counter-hate speech on Twitter.