The size of under-reporting bias in recorded transnational terrorist activity

Summary.  We address an apparent gap in the applied terrorism literature providing an estimate for the size of under-reporting in transnational terrorist activity. The method that is suggested is computationally straightforward and takes into account the stochastic interactions between terrorism, polity and press freedom in a manner that utilizes their sample properties. The outcome from the application of this metric is that underreporting bias is indeed present and quite sizable.