Article révisé par les pairs
Résumé : One well-known characteristic of participatory websites is that the distribution of contribution levels is highly skewed: most people who make use of the service contribute only a little, but a small minority, often known as ‘power users’, contribute a lot. These power users are understudied in the literature on online democratic participation: this article aims to fill this gap. Based on a unique observational dataset of hundreds of thousands of users of an electronic petitioning platform, we show that having more free time is an important determinant of becoming a power user, as is having a positive initial experience with the site. We also show that power users are both more effective than regular users and that their interests differ substantially from ‘normal’ users: meaning that these small groups have a powerful (and distorting) influence on overall outcomes for the site.