A Closer Look at Reporting Bias in Conflict Event Data

A re-assessment of reporting bias in event-based violence data with respect to cell phone coverage

“…We agree with Weidmann's (2016) assessment that reporting bias is a serious problem and represents a true challenge, especially when trying to infer the effects of ICTs on violent collective action. The additional sensitivity analyses we present here suggest that there is no overwhelming indication that reporting bias is completely driving the findings in Pierskalla and Hollenbach (2013).…”

“…He then creates sub-sets of the data (windows) that include 50% of the violent events in 2008 (444 events), changing the composition of the violence data by sliding the window by 10 events per subset. Weidmann (2016) shows that the marginal effect of cell phones decreases for samples with more fatalities, and the 95% confidence interval covers zero for about one-third of the estimated models, which is consistent with reporting bias being an alternative explanation for the original finding. This is a useful and straightforward approach, but requires the analyst to make a number of ad hoc model specification choices that might affect the conclusions of the sensitivity check.…”

“…If bias is driving the finding, then with increasing fatality rates, the estimated coefficient for cell phone coverage should decrease. To create the sensitivity analysis, Weidmann (2016) orders all violent events for 2008 by the number of fatalities. He then creates sub-sets of the data (windows) that include 50% of the violent events in 2008 (444 events), changing the composition of the violence data by sliding the window by 10 events per subset.…”

“…The data set provides a best estimate and a high estimate. To order the events by severity, Weidmann (2016) uses the high estimate. There is no clear reason to prefer the high over the best estimate and vice versa.…”

Different Types of Data and the Validity of Democracy Measures

“…On the one hand, there is likely to be a reporting bias because reliable information is often not readily available (see Fariss, 2014;McNitt, 1988, pp. 94-99;Weidmann, 2016). The perpetrators normally have a clear interest in keeping the correct number secret and it is often difficult to know why a particular journalist has disappeared or died, or whether they were imprisoned due to a legitimate use of their freedom of expression or some other reasons.…”