Online social networking (OSN) websites such as Twitter and Facebook are known to have a wide heterogeneity in the popularity of their users, which is counted typically in terms of the number of followers or friends of the users. We add to the large body of work on information diffusion on online social networking websites, by studying how the behavior of the small minority of very popular users on Twitter differs from that of the bulk of the population of ordinary users, and how these differences may impact information diffusion. Our findings are somewhat counter intuitive. We find that on aggregate metrics such as the tweeting volume and degree of participation on different topics, popular users and ordinary users seem similar to each other. We also find that although popular users do seem to command an influential position in driving the popularity of topics on Twitter, in practice they do not affect growth rates of user participation and the causality of popular users driving event popularity is hard to establish. Our observations corroborate the findings of other researchers who show that user popularity in terms of number of followers does not translate into driving event popularity, but that event popularity may be driven by extraneous factors to do with the importance of the event. 
The rich and middle classes on Twitter: Are popular users indeed different from regular users?