Samenvatting

In our 2017 report “Profielen van outlaw bikers and outlawbiker clubs” we concluded, “Dutch members of outlaw motorcycle gangs disproportionally frequently have a history criminal justice contacts”. The attorney representing the Hells Angels in the civil law suit filed by the Dutch public prosecutor requesting a civil ban of the Hells Angels, after consulting an expert methodologist, challenged this conclusion due to the possibility of type 2 and type 1 errors in constructing our sample from a police gang database. Here we calculate the proportion of convicted Hells Angels members under different levels of potential bias resulting from these errors. We find that a realistic estimate of the proportion of convicted individuals among the Dutch Hells Angels membership is between 58-96%, which, at a minimum, is roughly twice that in an age-matched population of male motorcyclists who are not members of an outlaw motorcycle club.