Audience size and activity levels across <i>k</i>-cores.

<p>Panel A shows the distribution in number of followers (or reach) across <i>k</i>-shells. Panel B plots the distributions in number of tweets sent (or activity) across k-shells. Panel C shows the effects on overall reach and activity of removing <i>k</i>-cores progressively, starting from the lowest or most peripheral as illustrated by the networks below the horizontal axis. Removing the first five <i>k</i>-cores results in a drop of slightly more than 50% in total reach capacity, suggesting that the sphere of influence of core participants is much reduced without peripheral contributors. The random benchmark is based on 10,000 permutations of the data where assignment to <i>k</i>-cores is randomly re-shuffled; this benchmark can be interpreted as a line of perfect equality, i.e. a scenario in which all <i>k</i>-cores contribute the same amount to overall activity and reach.